From Cafe Hayek:
I own my business and, unlike an employee, I have the option to work as much or as little as I like. At some tax rate, the marginal dollar won't be worth earning. I'll fire some employees, scale down the business or retire altogether and stick my money in tax advantaged muni bonds and do all the traveling and relaxing I can't do now. . . . If I'm not ready to retire and the tax rate gets too high, I may just immigrate to another country because it's very easy for me to get almost instant citizenship in any other country. I respond to incentives and I'm not incentivized by enslavement and neither is anyone I know.