That is rather inaccurate. Short term capital gains tax rate is 37%, period. Long term capital gains and income tax (wages, interest income, dividends, etc.) is 0%-37% based on your income tax bracket. I'm pretty sure the most of us fall in that 12%-24% range. I just went through all of this tax rate crap to determine the amount of mandatory beneficiary IRA distributions I could take and stay within our current tax bracket. I think we had to stay below $189K or so to be in the 22% bracket.
Your statement is only accurate if you are single and earn $539,900, married filing jointly $693,750, putting you in the top marginal tax bracket.
All of that notwithstanding, the point is that GUARANTEED earnings for a short amount of time with ZERO risk (unless your bank fails and your money is not FDIC insured) is pretty hard to compete with. Having said that, I admit that I am heavily invested in stocks and have been for over a decade, but that is not money that I will ever need to access until I retire.