Sanndy

Rich assholes spending their money on expensive luxuries fund the luxury economy, which finds its way to the regular economy.

The word you are looking for is investment, while what you’ve described here is consumption. Investment is far, far better than consumption. One is adding to the market, and the other is removing things from the market that could otherwise have been put to much better uses.

Capitalism has been working so far because the economy has been growing, so even if you are poor right now and someone is filthy rich, you are still guaranteed to be better off in the not-so-distant future. However, the world’s growth is slowly stagnating, and already has stagnated or even reversed in many developed nations. That spells doom for anyone who was not able to climb out of the economic pit. Living in a stagnant world ruled over by a handful of oligarchs for the rest of eternity, or until the next economic boom (unlikely) is not a pretty prospect.