In a recent article I condemned the foolish people of California for approving a referendum to raise the state’s top tax rate to 13.3 percent.

This impulsive and misguided exercise in class warfare surely will backfire as more and more productive people flee to other states—particularly those that don’t impose any state income tax.

We know that people cross state borders all the time, and it’s usually to travel from high-tax states to low-tax states. And we’ve already seen some evidence that the state’s new top tax rate is causing a loss of highly valued jobs.

This mobility of labor and talent is one of the reasons why California is going to get a very painful lesson about the Laffer Curve.

Politicians (with help from short-sighted voters) can raise tax rates. But they can’t force people to earn income. Now it looks like one of the super-rich is fed up and looking to make himself less vulnerable to California’s kleptocrats.

ESPN quotes professional golfer Phil Mickelson as saying: “There are going to be some drastic changes for me because I happen to be in that zone that has been targeted both federally and by the state and, you know, it doesn’t work for me right now. So I’m going to have to make some changes. … If you add up all the federal and you look at the disability and the unemployment and the Social Security and the state, my tax rate’s 62, 63 percent.”

He’s actually overstating his marginal tax rate. I suspect it’s closer to 50 percent. But so what? It’s still outrageous and immoral that government is confiscating one-half of the income he generates.

Medieval serfs were virtually slaves, yet they only had to give at most one-third of their output to the lord of the manor.

I hope he’s serious and that he escapes from the Golden State’s fiscal hellhole. If he does, what will it mean for California government finances?

Wikipedia estimates that Mickelson’s 2011 earnings topped $62 million. But let’s just assume his annual taxable income will be, say, $40 million for 2013 and beyond. With a 10.3 percent top tax rate, California would collect about $4.12 million per year. And Mickelson apparently thought that was tolerable.

But guess how much the politicians will collect if he leaves the state? I’m tempted to say zero, but they may still get some revenue because of California-based tournaments and other factors.

I can say with great confidence, however, that California won’t collect $5.32 million, which is probably what the politicians assumed when they seduced voters into approving the 13.3 percent tax rate. After all, that assumption only works if Mickelson is willing to be a fiscal slave.

As such, I’ll also state with certainty that California’s politicians won’t collect $4 million if Mickelson leaves for another state. Or $3 million. Or $2 million. Or even $1 million.

The best they can hope for is that Mickelson decides to stay in the state while also reducing his taxable income. In that scenario, the politicians might still pocket a couple of million dollars. Not as much as they collected when the tax rate was 10.3 percent, and far less than what they erroneously assumed they would get with a 13.3 percent rate.

Most rich people—whether they’re golfers, celebrities, investors, or entrepreneurs—have considerable control over the timing, level, and composition of their income. And they can afford to move.

This is why you don’t want to be on the downward-sloping portion of the Laffer Curve.

Economist Daniel J. Mitchell (Ph.D. in economics, George Mason University) is a senior fellow at the Cato Institute.