And empathy doesn't require kindness.

Yes. I don't want you to be kind to him either. But the way you're phrasing what you're saying it gives off the impression that you're actively ridiculing him because you're annoyed at him for publicly complaining despite growing up in a household with seemingly a lot of money. Perhaps it's just a case of miscommunication/misunderstanding but that's what I take issue with.

I agree with you that he has to toughen up eventually because otherwise he'll just end up a broken person. But he's 14. He's still a kid. To learn to live with a fucked up upbringing is a process that doesn't happen overnight and it especially doesn't happen as long as you're stuck in that environment. So let him vent, let him complain, let him rebel, it's part of that process. Ridiculing him for it is as contra-productive as coddling him would be. That's the point I'm trying to make.

He wants to come on the internet, say he is a grown man and talk he gets treated like everyone else.

Where did he say he's a grown man? He complained about having to becoming an adult without having anyone to actually teach him. Which is a valid complain for a kid to have.