A lot of the same people also recently bet huge amounts of money that blockchains and crypto would replace the world's financial system (and logistics and a hundred other industries).
A16z and Sequoia made some big crypto bets, but I don't recall Google or Microsoft building new DCs for crypto mining. There's a fundamental difference between VCs throwing spaghetti against the wall and established tech giants steering their own resources towards something.
How did that work out?