My not owning shares of a company doesnt make them any less bad, at least if in own shares I can vote on who is elected to the board and what direction they take things.
If enough like minded people with money wanted to do to corecivic what elon musk did to Twitter the way to do that is by owning enough stock to do a hostile takeover and force the company to shut down.
Thats how you use capitalists lack of ethics against them.
I wish I could find like minded people but I'm not a skilled organizer, I'm too much of a pessimist.