More availability -> lower prices. A lot of people hold because the income:expense ratio on their property is really great. If your rental home goes from $1000/yr in taxes to the $15k/yr that every new homeowner is paying, you'll see that cut into your rental income. You could try to raise rent by $1000+/month but that won't happen because salaries aren't gonna rise that fast. So, you'll sell.

Thus, as a homeowner, when you go to sell then you will get less... A lot of these homes will fund peoples retirement in other regions. I see a lot of people in older age (who don't want to deal with renting, don't want to pass the home down, or didn't save for retirement) selling their homes here and moving to somewhere cheaper. They get to live a nice life off the gains they made.