Most of the bubble is because of rent control aka prop 13. There's plenty of research showing that artificially limiting rent on part of the housing stock squeezes the price on the remaining units and causes the rent controlled units to never appear on the market. Look at data on NYC for an extreme example of this.
In NYC around half the housing is rent controlled and a tenant stays for over twenty years on average. These units pay roughly a third of the rate of a non rent controlled apartment. In non-rent-controlled apartments the cost is over the three times as high and the average person stays for less than two years.
In NYC these units have been rent controlled for so long that most have passed down from the original owner. However, they still only tend to be sold upon death because renting them out illegally is incredibly lucrative, often enough that the owner can live off of the proceeds.
So yeah rent control effectively removes that part of housing stock from the market permanently. It's too hard to prevent people from profiting off their rent controlled units so it just results in a racket.