Perhaps, but as the higher the tax rate, the higher the greater the incentive to avoid taxes. As PG mentioned in his essay, when the marginal tax rate was at 90%, there was a lot more tax avoidance and lavish, wasteful benefits companies offered their employees in lieu of wages (health care, housing, first class flights). If the tax rate were high enough, the government would actually bring in less revenue as there is more avoidance but it would also have negative externalities like padded expenses, people fleeing the country, shell companies, etc.