Every rental house is owned by someone and that someone hopes to make a profit at some point. It is reasonable to assume that when the market is on its way down some of these rentals will be sold. There can never be enough rental properties to accomodate everyone in the region, so it CAN’T be the answer for most people.
While we’re at it, the rental market can become just as volatile at the sales market if the supply/demand dynamic changes a lot. The only difference is that a rental tenant can’t make or lose money by participating in that market.