That's kinda the problem, how to incentivise making housing but dis-incentivise just buying them as an investment. Taxing it just makes renting more expensive,

That's kinda the problem, how to incentivise making housing but dis-incentivise just buying them as an investment. Taxing it just makes renting more expensive, high interest rates makes even less people be able to afford one in the first place, and you still need some rental properties as many people don't want to immediately get the forever home. Regulating renting would make many people bitch and whine about their freedoms to do what they want with thing they own (and, well, rightly so) so there is not that much options left. Cities could build then rent housing (with maybe option to buy out at discount if you lived there for few years) but good luck trying to beat private investors without some heavy legislation on it.