This is an ad nauseam repeated false statistic. That number counts household members - meaning ~70% of population owns property when you account children in those households (and grandparents). And those children are definitely going to need homes of their own... Or I guess you'll have situation akin to one in my home country where >60% of 25-34 y.o. young adults live with their parents, with all the economic and psychological stunted development that entails.