Why are Blackrock assests under management so much more than its market cap?

I dont understand how they manage trillions but only make a few billions in earnings? What are they doing with all the other assets? Do people just give them assets to do nothing? Sorry for the basic question but I cant find the answer online.

Also, are they an actual threat for civilization or thats just a lazy conspiracy theory? I get attacked by conspiracy people just for trying to understand Blackrock better lol