Earlier quoted context omitted.
I’m not sure either of statements really excuses the underperformance. You either beat the market or you don’t. It’s relative. He could lose money but if he loses less than the broad market, he outperformed. And sitting on a pile of cash is a negative, a lost opportunity. That said 20 years is arbitrary, however it’s not an insignificant period of time. It’s two decades! But my final point is that Buffet isn’t an inv…
When making a comparison like that, the endpoints really matter. How many of the last 20 years has he been beating the market? And the next 10? Today is at an extreme in valuations and of course everyone who is betting on a fall will look bad until suddenly they don't. It's currently not possible to say whether sitting on cash is stupid or wise, the next few years will bear that out one way or another.
It's 20 years of failing to beat a simple "invest in indexes and forget it". So basically an adult who followed index investing for the last 20 years can say "I have higher returns than Buffet".