What is stopping it is the fact that the "wealth" they are being taxed on doesn't actually exist, so by starting a company and getting investment you create tax liability that is impossible to pay.

Early stage companies have a high valuation on paper as an artifact of selling small amounts of equity for relatively large sums of money. This leaves you with purely theoretical wealth in the form of equity which you have not yet sold, and potentially can't sell.

As a concrete example, let's say your tax rate is 15%. If you start a business, and give an investor a 10% stake in that business in exchange for $1M, your remaining 90% stake in the company is now worth $9M. Congratulations, you're wealthy! Now you need to "pay your dues" of 15% of that $9M... good luck with that. You are now bankrupt and deeply in dept to the government.