Blackrock and Vanguard's customers (your 401k) own some part of everything. They just manage it.

Blackrock does vote its shares for you most of the time, which can be a big impact, but my understanding is the practical impact of this has mainly been that BlackRock tells companies to care about climate change more and then Republican attorneys general get mad at them for this and write threatening letters about it.

The cycle where CalPERS puts all their money into tech startups and makes Silicon Valley VCs rich is more interesting I think.