If we hit the saturation point for tall apartment buildings, the land is less valuable (since you can't extract as much value from it), decreasing the land value taxes (and thus, incentive to leave homes). Lower land value taxes incentivize constructing more modest apartment buildings, as those will now be profitable. This process continues until housing supply meets demand.
Also many people prefer living in single-family houses. The bay area is full of people who won't sell their single-family house even though the value has gone up 20x. They wouldn't abandon their properties unless they had to. And if they have to it means they can sell them for a lot to a developer who will profitably build an apartment.