> If I start a company and it gets valued at 30 million dollars, why should the government be allowed to force me to sell my company to pay their wealth tax?

I don't know the specifics of this proposal. But I live in a country that has a similar wealth tax, and it doesn't work that way here. When you found a company, its shares remain valued at nominal value for tax purposes, until you sell or transfer them. Only after that they'll be taxed as wealth.