The writer, founder and chair of Dimensional Fund Advisors, compares prediction markets to drugs, warning they encourage gambling over long-term investing. These platforms let users wager on real-world events like elections and flight delays, creating a "lottery effect" especially dangerous for young people chasing instant thrills. A Betterment survey found over a quarter of Gen Z treat sports betting as part of their long-term strategy, while more than half have redirected investment money to betting.

Global trading volume on major prediction markets surged from under $5bn in September 2025 to $23.8bn in April 2026, per Pew Research Center. The SEC is considering permitting prediction-market ETFs. The author notes these markets are worse than zero-sum: expected returns are negative, akin to betting against a Las Vegas house with insiders tilting the scales.

True public markets work differently, with transparent pricing and investor protections allowing fair long-term growth. US stocks have delivered 10 per cent annualised returns for a century. The author concludes that understanding how real investing works helps people avoid speculation and build enduring wealth.