It’s interesting how that idea has been around for so long - it wasn’t new when A Random Walk Down Wall Street came out in the 1970s - but there’s a never ending supply of people who think they can beat the odds and investors who want to believe.
Don't let nit-picky facts like that institutional investors control substantially more capital than retail investors get in the way of a good narrative.
No, there is no good reason for Tesla to be valued the way it is - but there is no shortage of people willing to buy it without putting too much thought into the price, either.
* https://en.wikipedia.org/wiki/Mutual_fund
Perhaps the Dow Jones was small enough of an index to keep track of manually, but things like the S&P 500 would have been harder (never mind the Russell 3000 or total market):
* https://en.wikipedia.org/wiki/S%26P_500_Index#History
Then there had to be interest from investors. So it's not entirely surprising that it took until the 1970s with Vanguard to really create something.
https://www.goodreads.com/book/show/106835.The_Intelligent_I...
Based on how the stock market didn't die during the pandemic vs. how many people lost their jobs, I'd say they are right to believe that.
And if you're just a regular wage earner with some cash, seeing the labor market being dropped on its head, maybe this stock market thing might be a good idea to try. I mean, some people definitely bought stocks with the $1200 stimulus check. Getting into the stock market (which ended up doing unreasonably well) was a way to hedge against losing your job (which you had a higher likelihood of losing).
I would say it’s far too early to draw conclusions about the pandemic stock market, and certainly to say that an observation which has generally been supported by data for the last century or so is no longer valid.