do you mean current and last 18 months house price growth is unsustainable? If so i agree, but to think over a period of slowing down and wages start to uptick again, same thing will happen again, just like the last opportunity in 2011.
This crash/ doomsday scenario will play out in the minds of non owners for ever, and the next opportunity will also pass them by as they wait for the big crash dream, only to see over time that just inflation will erode their buying power.
The irony of you saying banks will not lend will perhaps be lost on the bears also