The 50-year mortgage idea really is an IQ test for those that don't understand how to leverage debt. With a lower payment & interest rate, if you put the savings (the difference between your old & new payment) into an asset that grows faster than the mortgage interest rate which is obviously Bitcoin then you just covered the difference in total interest - and then some. You don't have to do a 50 year mortgage if you don't want, but if the terms are favorable, you can bet I will.