This is the best way to end America's entrepreneurial culture.
Most founders I know endure 100+ hours of work/week because they are obsessed with their mission and the impact they can have on the world.
They make < $100K / year, fly economy, and live modest lives. The average American doesn't want their life.
Just because their company's valuation is growing doesn't mean they are "wealthy".
When you impose a > $100M tax on illiquid stock, they will declare bankruptcy or flee the country.