a) the idea that we’re ‘behind’ in physical supply (in an overall sense, pan-nationally) is a myth — because if it were true, then building permit numbers would either be increasing or staying constant, in proportion to population growth (provided demand was rational – meaning, housing is being built only for resident citizens who need it); and

b) that developers / builders will never build excess housing to the extent that prices would decline. They control the amount and rate of supply. They have the power to throttle (down) supply if they so choose, by simply slowing down the rate of building. It is simply not in their interest to ever build more than what is ‘demanded’.