Because the propensity to spend an extra dollar of income is nearly 100 percent for the government, but much lower for individuals. If you give Congress an extra dollar, it will spend every penny of it. If you give Americans an extra dollar, they might only spend 90 cents of it. Almost none of the tax-cut opponents really doubt this. In fact, many are quite open about their desire not to cut taxes so that the federal government can spend the money on health care, child care, the schools, foreign aid, congressional pay raises, etc.
Wealth creation is the ultimate form of saving.
In the past 18 months, Japan, Germany and France have all cut their income taxes. They're on to something. European economic ministers have started to begrudgingly concede that their taxes are simply too high to compete internationally. They finally seem to have taken off their socialist blinders to discover that taxes matter a whole lot in today's hyper-competitive global economy. It probably is.