This shit is just embarrassing for you dolts.
Look - the claim is not that "tax cuts for the rich" helps everyone else. That's the bogus mischaracterization by Democrats.
The claim is very simple. Raising marginal tax rates increases revenue to the federal government, but as the marginal rates go up, the returns diminish until at a certain point, higher tax rates actually reduce revenue collected by stifling growth and encouraging tax avoidance and evasion. This is a principle of economics. So, the idea is that it MAY be revenue positive to lower marginal tax rates. However, that is not limited to "the rich."
Also, the idea that lower taxes is better for economic growth is not seriously disputed by anyone, including Barack Obama who stated explicitely "the last thing you want to do is raise taxes during a recession."
Why do you think that is the last thing you want to do? Because taxes are a cost, and if you raise taxes it makes things on which the taxes are applied more expensive and as the price of something goes up, downward pressure is put on demand. This is not controversial. If you raise taxes on a business, for example, then it's more expensive for that business to do business. The higher the taxes, the harder it is for that business to stay in business. There is also less money in private hands to save, spend or invest.
I've never heard a Republican -- EVER -- say "tax cuts for the rich." That's a Democrat thing. FFS. Bush, for example, did not just "lower taxes on the rich." He raised the bottom of the tax brackets -- I.e. he raised the amount of income someone needs to make in order to pay zero percent taxes, thereby exempting more people from paying any federal income tax at all. He lowered ALL tax brackts for everyone paying any taxes whether they made $25,000, $30,000, $40,000 or $50,000 or more.
You can't debunk the Republican "myth" that "tax cuts for the rich" are super awesome, because that isn't the Republican position. The Republican position is that lowering tax rates may result in an increase in revenues collected by the government because it helps increase the tax base from which taxes are drawn -- it's like having a 50% tax rate on 10 people making $100,000 per year and collecting $500,000 a year -- or lowering the rate to 25% but thereby helping expand the tax base to 25 people making $100,000 per year and taking in $625,000.
And, it is not a myth that lower taxes is better for people who pay taxes. What the fuck, folks?