I can't speak for others, but this doesn't match my thinking at all.

I want to heavily tax the ultra rich because money is power, and vast inequality in power is undemocratic and just plain dangerous.

I don't really care if somebody buys ten massive yachts. It's annoying and seems wasteful but it's not worth too much of my attention.

But it's another matter if somebody buys politicians, laws, social change. The issue with someone like Elon Musk isn't that he owns a private jet, or even that he owns a rocket company, it's that he bought his way to taking an axe to major parts of our government by pouring unimaginable amounts of money into buying a presidential election.

It's not about grabbing stuff, it's about preventing people from accumulating too much power. The ultra-wealthy should be heavily taxed for the same reason the President shouldn't be given unlimited power to do whatever they want.