Andrew Yang's plan for a GMI of $1k/mo seems like a non-starter for any number of reasons. Senator Sanders' statement that "billionaires should not exist" also seems like an internet meme with no chance.
“Alleviate both indigency and extravagance.” -- José María Morelos
There must be a third alternative. Great success should not be penalized, but neither should it be allowed to suck all the air out of the economy. The simple economic fact is that billionaires cannot spend enough to keep an economy going, and having too many of them inevitably leads to collapse.
Therefore we need some mechanism for the über-successful to share their success in a socially-conscious yet still personally-gratifying way. Some charitable pathway that rich people would like to participate in, and that actually HELPS the less-fortunate. I don't know if public works would fulfill that need -- how many Guggenheim Museums do we need? -- nor would starting businesses to employ the unemployable be very satisfying (rich people want to get richer, not run failing companies).
I'll be giving this thought and check back if I think of anything.