Why do you think stock has value? It's because it's a piece of ownership of the company. Yes it's a way for the company to get some capital, but it's also the way for private company owners to cash in on their company being successful.
Why is being paid in ownership insane? It's directly tied to the performance of the company, if the company does well the stock does well, and it's incentive to drive the company in the right direction to reward employees of all levels with stock.
It's insane to tax this ownership, it's not worth the amount it looks like. If an owner had to sell their stock, the stock value would plummet not only because of the huge uptick in supply of stock available to trade, but because the person running the company now has little to no stake in the success of the company.
You know who this also screws over? All the middle class people trying to retire on their stock values going up. You tax wealth, stock values will plummet, and there goes the middle class retirement, no thanks!
Of course I know what hedge funds are, and that people manage them. It's all about actively buying and selling stocks, bonds, and options.
You can call it a terrible retirement vehicle if you want, but it's literally how the middle class is able to retire. From 401k, to Roth IRA, to other much every other retirement account available to the middle class, it's based on stocks, and it's worked well for a ton of people.
It only bankrupts idiots like those on /r/wallstreetbets or those who put all their money into one stock. Yes the market may go down, and it may go down a lot, but that's not going to make you bankrupt unless you make extremely dumb choices.
Luckily most retirement plans come with a target date fund, which is an easy way to diversify and get basically guaranteed gains.
Also, it's the only retirement the middle class has, so you can't destroy it.