The bubble will burst sooner or later, at some point nobody will want BTC.
subprime mortgage loans seemed to be safe at that time,
if they can't pay back, banks will just sell their home
that's why banks gave loans to virtually everyone. But you know what happened in 2008.
BTC is backed by very weak concept mining,
mining itself isn't strong enough to justify current BTC price.
If miners can't pay they will just sell their ASICs....
wait a minute.

You are right, It's a very similar mechanism at work here... just that homes have some intrinsic base value because of universal demand (everybody needs to live at some place).