> So when a new home owner buys something and suddenly the value drops $100k and the bank wants the money I do feel slightly sorry for them.

I feel a little sorry for them but they are not missing the money total of "the whole house". They can sell the house, have a shitty $100k debt, a tale of woe, and hopefully a better idea of how to go about spending money they didn't have.

I feel there are too many people who "borrow as much as they can for the best house they can get" rather than being sensible about their money and using a mortgage as a hedge against paying rent and future rent raises. Some of them make it, some of them don't.