Plus, they're getting real world training data from everyone who either hasn't or doesn't have the ability to opt out of their stuff being used.

For my personal stuff, I don't opt out of training for this very reason. What's more, I resent Stack Overflow and Reddit etc. trying to gate-keep the content that I wanted to give to the community and charge rent for it.

I used to intentionally post question-answer style posts where I would both ask the question,wait for a while, then answer the question on both Reddit and Stack Overflow. I don't do that anymore because I'm not giving them free money if they're not passing some of the benefit on to the community