They aren’t and they didn’t.
> Being a self-made billionaire means they created a billion dollars of value. They didn't take it from you or anyone else.
Nobody is a “self made” billionaire. That value you’re talking about didn’t just spring into existence. It had to come from somewhere. There is always a source.
Who flew the rocket? Who built the rocket? Who built the parts for the rocket? Who mixed the fuel?
Building big ambitious things is a good thing. But consolidating an amount of money that nobody could ever reasonably spend into the hands of one person (especially when that money is just the excess value produced by the workers) is unethical and unneeded.