So for the cost of keeping $15000 stuck in a checking account for say 10 years, you get a whopping $927.31. You'd get more money back dropping that into a high-efficiency AC system or solar panels.

Meanwhile, most people don't even have $15000 lying around with nothing else to do. My understanding from surveys done by various companies is that 60% of Americans don't even have $1000 in savings. And those with beaucoup money are negotiating their own loan rates, because there's better places to park their money for long-term interest.