I think that is a terrible idea because it does nothing to address the real problem - economic growth being largely captured by ultra rich people. Sure everyone who is invested in stock market will be richer, but people who need most help are not buying stocks.

Taxation is hard, so far Sam Altman's capital tax is least worst option I've heard: https://moores.samaltman.com/ . It does have it's deficiencies... It's wealth redistribution, it might slow down or even completely stunt economic growth, and given current political climate and corruption and is highly unlikely to be implemented. At the same time humanitarian value alone it would bring is so astronomical that I believe we must try it. It would also greatly expand middle class which should boost the economy long term.