Of course it is that simple. It worked for decades after WWII in the US. As long as capital gains are taxed lower than income, that is where the rich will put their money. If they only get richer when their employees and companies and society as a whole get richer (rathern than just them personally), then that is where they will put their money.

In the EU we still have lots of countries with 50% or higher marginal income tax rates, and business rates at 25% with limited deductions. Lots of us successful small business owners don't flee the country because we like living in a civil, thriving society and understand that paying our fair share of taxes is the price we pay for that.

The problem is that the US government has been bought by the ultra wealthy and converted into a tax haven.