This goes against just about every standard defense of the ability to be rich: that rich people are job creators, that they power the economy by buying things, etc. Why should we discourage them from employing people and buying things? I don't want a loan (that needs to be repaid) from a bank from a rich person, I want the rich person to either employ me or buy goods and services from me.

Actually, that's another point - does employment incur your "sales" tax? If not, it's more advantageous to hire a private chef or driver than to pay for a restaurant meal or a taxi trip, which makes the tax regressive - there's a discontinuity when you're able to hire someone instead of getting a service from a business.