I hear this "tax them out of existence" but not anything specific. Higher tax rates are one thing. Punitive tax rates to make sure they do not exist are another. I would have concerns that would drive entrepreneurship overseas. Is one billion the magic mark? Would someone who is only worth $120 million but has created a gold mine that is now bringing in $90 million a year also going to be kneecapped or not until the billion mark?
And even coming from wealth, they had to do something. Musk's wealth is not just growth of inheritance.
Long term employees often do have an ownership stake. If you can't vote, you are an investor, not an owner/shareholder. That change would require a complete overhaul of the system as the price paid to simply invest vs own would need to be far different. Employees are also passive ownership.* If employees are given ownership, that is essentially just taking a portion of their compensation and forcing them to buy company stock with it. I would guess there are studies of differences in those that give ownership for employees as part of compensation vs those that do not. If you work for NVDA over the past decade, it is a great idea. If you work for MSTR, what seemed like a great idea is now a horrible idea. Ownership has risks. I have been a full owner, shareholder, and employee of places I have worked. The mindset is completely different in each. Having the place run by an employee mindset would be a disaster. But, it would not matter as contrary to what you are saying, there is a lot of work and risk to setting up the company. The person/group that sets it up then if successful has to basically hand it off to others is not gonna work as a system.