The possibility of people leaving really has little to do with the Laffer curve. It's just the simple observation that if taxes are extremely high, people will

The possibility of people leaving really has little to do with the Laffer curve. It's just the simple observation that if taxes are extremely high, people will change their behavior: for instance, if you have a choice between staying in your stable job with mediocre pay and middle-of-the-road tax rates, or taking a big risk to start a new business, but be subject to such high tax rates if you succeed that you'll make no more money after taxes, very few people would even bother starting that new business.