Earlier quoted context omitted.
Not sure about the US but fixed-rate term in Australia is about 5 years. Nobody would give you a 30 year fixed rate. You'd eventually have to pay 6% on the $1M.
30 year fixed rate is actually the “normal”/common mortgage in the US. I moved to the US from the UK, where mortgages look more like Australia’s, and I still find it amazing you can fix such a low rate for so long here.
Before the creation of the enormous state-owned insurance corporations and government programs to drive down those fixed rate mortgage costs, American mortgages were usually short-term, with giant balloon payments. Those short-term, balloon-payment mortgages went bust in huge numbers during the Great Depression, creating pressure on the government to "do something."
Say what you will about American housing policy, but those 15- and 30-year mortgage arrangements are very stable.