Some estimates put the number of vacant homes upwards of 30% a few months back, and it's been climbing
It's not about a lack of supply, it's about homes being both an investment and a basic need - someone like Black Rock can go into a small town in Georgia, snap up every property that goes on the market, then dictate rental prices while jacking up the house prices by bidding on everything. Even if they greatly overpay, by doing it a few times it drives up the valuation of the entire area, overall making their net profit grow
And it's not just Black Rock, it's a bunch of investment companies doing this everywhere. They have the same goal and their interests are aligned - they're not competing for tenants, they just want to jack up the values and use homes like stock investments
It all comes down to "well, sure we might have plenty, but if not for capitalism how could we decide how to divide it?"
But any solution has to promote self-interest as a virtue and can't take things away from people who currently own them, and also must conform to a bunch of myths we have about "how the world works"