Tax the rich and start increasing taxes on properties that sit vacant for extended periods.

That apartment hasn’t rented out in 2 years? Taxes go up. As soon as it’s rented, they go back down. Make it tiered, and the tiers don’t just reset once rented, they gradually decrease back to the original level if it is continually rented.

Do something similar for empty office space. Encourage the bastards to either lower rental/lease rates until it’s actually reasonable, or to convert excess office space to residential housing.