Why should the public profit from the successes undertaken by a self-selected few people? There's no inherent right of people to take other people's money and burn it to the ground in pursuit of some particular ideological end or material goal.

If you want to take from the winners then you need to cover the losers. Now we could have a nice balance (reasonable taxes spent well for the public good) where both sides benefit but if you want to go extreme at the top then don't expect everything to work out.

Either way, nobody has yet answered the question I've asked a dozen times: How does a govt poorly spending trillions get fixed by spending a few more billion?

Who underwrites the investment risks taken by Bill Gates exactly?

Wealth mobility in the USA is pretty high. It's entirely possible for billionaires to stop being billionaires, or for people to temporarily become rich and then lose it again. Lots of stories like that out there. Elon Musk has made fortunes and lost them several times, I think.

Taxation is not an illegal or immoral appropriation of property

Obviously it's not illegal by definition.

Immoral? Yeah, I think a 100% tax rate i.e. communism would be deeply immoral. And taxes today are very high, and frequently lead to huge misallocation of resources. I think you could easily argue for lower taxes from a moral position.