Luckily humanity learned to build skyscrapers eons ago. You're forgetting about the many people who would easily shift to condo housing if it was 2x cheaper, but aren't because it's marginally cheaper than a SFH, and they don't want to put 3x their net worth into a condo that will probably end up financially worse than a SFH. So you still have a huge population that would live in condo's if it was more affordable. And housing pricing is all about the margins of the market, so you fix that imbalance and you make the housing market a whole lot more healthy.