Personal product preferences are often the worst possible guide to investment decisions.
I remember when my family first got a GoPro. Revolutionary technology, stunning footage – everyone wanted one. Naturally, I thought: "This company is going places. Maybe I should buy shares." It's a seductive logic: if I love the product, surely others will too. A decade later, I'm thankful I didn't act on that impulse.
This instinct to invest in what we know and love feels intuitive. We use the products, we understand them, we see their value. But this emotional connection – what behavioural economists call "familiarity bias" – is precisely what makes it dangerous.
Back in 2014, GoPro went public and quickly hit a market capitalization of $10 billion with virtually no competition. Today? The stock trades around $1.87 per share – down 98% from its peak, with over $9.7 billion in market value lost.
What went wrong?
Smartphones killed the action camera star. Modern phones became waterproof, gained multiple lenses, and developed image stabilisation that rivals dedicated cameras. GoPro thought they were competing against other action cameras when they were actually competing against the most successful consumer device in history.
But here's the deeper lesson: loving a product tells you nothing about the company's competitive position or long-term viability. A great product is necessary but far from sufficient for investment success. In GoPro's case, every smartphone manufacturer became their competitor, each with deeper pockets and products consumers were already buying.
The Pattern Repeats Closer to Home
This isn't just an overseas story. Take My Food Bag – during COVID lockdowns, it seemed genius. The company went public in March 2021 at $1.85 per share, raising $342 million. Customers loved the service and bought shares. Many retail investors had enjoyed watching co-founder Nadia Lim cook on TV for years – hardly grounds for a wise investment decision. The result? Shares now trade around 25 cents – an 86% decline. As one fund manager noted, "It was a classic private equity exit, which has seen a lot of retail investors lose out."[1]
The timing seemed perfect. Lockdowns had created new habits. People were cooking at home more. The convenience model made sense. But investors failed to ask: what happens when lockdowns end? Is this a permanent behaviour shift or a temporary adaptation? How defensible is the business model? These are the uncomfortable questions that emotional attachment prevents us from asking.
As one fund manager noted, "It was a classic private equity exit, which has seen a lot of retail investors lose out."
Then there's Ryman Healthcare, beloved by many Kiwi families for good reason. My own family experienced the amazing care and kindness shown towards my late father during his time in the dementia care unit at Ryman in Havelock North. The quality of their villages is genuinely impressive. Yet despite these strengths, the stock hit $10.87 in December 2019 and now trades around $2.87 – down 74%. The investment thesis crumbled under construction delays and regulatory challenges, demonstrating that exceptional service doesn't automatically translate into strong investment returns.
This one hits close to home because the service was excellent. But gratitude and investment logic operate in different domains. A company can deliver outstanding customer experiences while simultaneously facing operational headwinds that undermine shareholder returns.
These three examples share a common thread: product or service quality created an emotional connection that clouded rational investment analysis.
The Evidence Against Emotional Investing
Behavioural finance research identifies "familiarity bias" as a major driver of poor investment decisions, where investors favour what they know rather than what performs best.[2] This bias is particularly pronounced amongst long-term investors who believe they're securing against volatility when they're actually concentrating risk.
The evidence against stock picking is overwhelming:
An Arizona State University study by Professor Hendrik Bessembinder examining over 28,000 stocks from 1926 to 2024 found that just 4% of firms created all net wealth in the U.S. stock market. The remaining 96% collectively matched Treasury bills over their lifetimes, and the majority of individual stocks actually reduced shareholder wealth compared to holding cash.[3]
Think about that. If you picked a stock at random, you'd have better than even odds of underperforming cash. The market's impressive returns come from a tiny fraction of companies – and identifying them in advance is nearly impossible.
Professional fund managers fare no better. S&P Dow Jones Indices' SPIVA Scorecard shows that after 10 years, approximately 85% of large-cap funds underperform the S&P 500, and after 15 years, around 90% trail the index.[4] Even Warren Buffett admits: "In 58 years of Berkshire management, most of my capital-allocation decisions have been no better than so-so."[5]
These aren't amateur investors. These are professionals with research teams, Bloomberg terminals, insider access, and decades of experience. If they can't beat a simple index fund, what makes individual investors think they can, especially when driven by product affection rather than analysis?
The Smart Money Questions
Instead of asking "Do I love this product?", evidence-based investors ask: How big is the addressable market? What prevents competitors from copying this? How strong are the financials? Is the company innovating fast enough? What could make this product obsolete?
These questions are deliberately uncomfortable because they force you to look beyond your emotional attachment. They require research, analysis, and a willingness to acknowledge uncertainty. Most importantly, they shift the focus from "I like this" to "can this company maintain a durable competitive advantage?"
The answers usually point to the same solution: diversification. Diversified index funds consistently outperform stock picking over the long term, providing market-matching returns while reducing the risk of catastrophic losses from individual stock failures.[6]
Diversification isn't glamorous. There's no story to tell at dinner parties about your clever stock pick. But it's precisely this lack of excitement that makes it effective. By owning the entire market, you guarantee you'll own the 4% of companies that generate all the wealth creation, without needing to predict which ones they'll be.
As a fee-only adviser working with evidence-based strategies, the real value isn't in chasing hot stocks or validating product obsessions. It's in building a robust financial plan grounded in decades of research, then maintaining discipline through market noise and emotional temptation.
This discipline is harder than it sounds. When GoPro was soaring, when My Food Bag was listing during lockdowns, when you're genuinely grateful for care received – the emotional pull to invest is powerful. It feels like you have special insight. You don't. You have an emotional connection clouding your judgment.
The most valuable thing a good adviser provides isn't stock tips or market predictions. It's the voice of reason when your emotions are screaming at you to invest in what you love. It's the person who asks the uncomfortable questions: "Have you analyzed the competitive landscape? What's your exit strategy? How does this fit your overall plan?" These questions aren't exciting, but they're essential.
Seek wise counsel, commit to a plan that aligns with your goals, and redirect that energy from stock-picking to living your life. Enjoy the products you love. Be grateful for excellent service. Just don't confuse these feelings with investment insight.
Your future self will thank you for choosing evidence over emotion.
Nick Stewart
(Ngāi Tahu, Ngāti Huirapa, Ngāti Māmoe, Ngāti Waitaha)
Financial Adviser and CEO at Stewart Group
Stewart Group is a Hawke's Bay and Wellington based CEFEX & BCorp certified financial planning and advisory firm providing personal fiduciary services, Wealth Management, Risk Insurance & KiwiSaver scheme solutions.
The information provided, or any opinions expressed in this article, are of a general nature only and should not be construed or relied on as a recommendation to invest in a financial product or class of financial products. You should seek financial advice specific to your circumstances from a Financial Adviser before making any financial decisions. A disclosure statement can be obtained free of charge by calling 0800 878 961 or visit our website, www.stewartgroup.co.nz
Article no. 437
References
My Food Bag Group Limited. (2024-2025). Financial Results and Market Updates. NZX Announcements. Retrieved from https://investors.myfoodbag.co.nz/
Devon Funds Management. (2025). "My Food Bag Investment Analysis." RNZ Business Interview, May 22, 2025.
Huberman, G. (2001). Familiarity breeds investment. Review of Financial Studies, 14(3), 659–680. https://doi.org/10.1093/rfs/14.3.659
Chew, S.H., Li, K.K., & Sagi, J. (2023). Home bias explained by familiarity, not ambiguity. Social Science Research Network. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3870716
De Vries, A., Erasmus, P.D., & Gerber, C. (2017). The familiar versus the unfamiliar: Familiarity bias amongst individual investors. Investment Analysts Journal, 46(1), 24-39.
Bessembinder, H. (2024). Shareholder wealth enhancement, 1926 to 2022 (Updated through 2024). Arizona State University, W.P. Carey School of Business. Retrieved from https://wpcarey.asu.edu/department-finance/faculty-research/do-stocks-outperform-treasury-bills
Bessembinder, H. (2018). Do stocks outperform Treasury bills? Journal of Financial Economics, 129(3), 440-457.
S&P Dow Jones Indices. (2024). SPIVA U.S. Scorecard Year-End 2024. Retrieved from https://www.spglobal.com/spdji/en/documents/spiva/spiva-us-year-end-2024.pdf
Berkshire Hathaway Inc. (2022). Letter to Shareholders. Annual Report 2022.
Malkiel, B.G. (2019). A random walk down Wall Street: The time-tested strategy for successful investing (12th ed.). W.W. Norton & Company.
Bogle, J.C. (2017). The little book of common sense investing: The only way to guarantee your fair share of stock market returns (10th anniversary ed.). John Wiley & Sons.
Fama, E.F., & French, K.R. (2010). Luck versus skill in the cross-section of mutual fund returns. The Journal of Finance, 65(5), 1915-1947.