In case of the US I’d say something must be done, either build more, or adjust economy in order to the middle class to be able to purchase in cities again.
Building more doesn’t solve the problem. There is vacant real estate already. If you don’t have a tenant for a property, you’re operating at a loss. A loss is a tax write off. With some creative accounting, it might be better to keep a place empty and increase the rate no one will pay you.
My solution is to devalue money.
A network of businesses and merchants that based on income, estate assets, and their contribution to the wield as recognized by the network, add a fee or a discount.
If you are living up to your potential doing good things, you can afford to spend less. If you have no income, but you are doing good to your abilities, potentially all basic needs are covered.
If you are hording value and causing harm, then you pay additional fees.
Combined, the fees cover the discounts. The economic gap grows smaller.