History has not shown that. It is easy to say that people beat the market by chance, but you should actually try calculating how many standard deviations from the mean some of these track records are. There haven't been anywhere nearly enough hedge funds to justify the most consistent track records being due to chance alone.

For illustration: assume any given fund has returns which simply approximate a normal distribution; i.e. their returns are theoretically just noise. Then the chance of the fund achieving a 2 sigma return in any given year is about 2%. We can model the odds of such a firm consistently exhibiting a 2 sigma return for 20 years in a row using a binomial distribution with n = 20 trials, k = 20 successes and success probability p = 0.02. Then we have

binom(20, 20) * 0.02^20 * 0.8^0 = 1x10^-34

There are firms which have consistently beaten the market by a significant margin for that long. Even if you relax the constraint to 10 years, you still get "only" 1x10^-17. At a certain point this becomes similar to saying that Steph Curry isn't actually good at basketball, all of his 3 point throws are just the expected outcome of lots of mediocre players existing who didn't make it to the NBA.

I do agree that retail investors should just invest in index funds though. And I agree it's extremely difficult to determine who has the genuine skill to beat the market before they've beaten it for so long that they're no longer accepting money.