Earlier quoted context omitted.
Say more. Why do I believe in the Capital Asset Pricing Model and Efficient Markets (both proven wrong) if I invest in Vanguard's cheap S&P 500 ETF? I invest in their S&P 500 ETF because it's the cheapest way to get diversified exposure to the 500 largest American companies, and I believe that the 500 largest American companies will be more valuable in the future as a combination of valuation, scale, and cash flows t…
I think the other commenters hit on the important points and anticipated my distinctions. Note that I said "on a significant level". That did not imply blind or absolute faith. There are other investment options to match your bullish outlook if you think CAPM and EMH are wrong to the approximation that suits your involvement, knowledge, and risk profile, but you chose an index ETF. Why?
Or maybe he just believes the market might stay irrational longer than he can stay solvent.