[clairity]

another way to look at this is that the number of people who need housing is higher than (far to the right of) the current market clearing price point (where the supply and demand curves currently cross).

building more at the high end shifts the whole supply curve down, not just the portion at the high end (this is because markets are defined by the interchangeability of the goods therein--i.e., fungibility). however, the rate of building is far too low to even meet the rising demand, much less to supply housing to everyone, so prices continue to rise.

the demand curve, which moves independent of the supply curve, has shifted up with the flood of high-salary developers into the market, so the new equilibrium price is still high and far to the left of the number of people needing housing.

all of those people between the market clearing price point and total needing housing are homeless (not all are on the streets however).

to get to the point where we can house everyone, we can shift the demand curve up with higher wages (for the bottom 80%). the supply curve shifts up (prices are higher) with high rents (e.g., land prices), zoning/other regulations, and nimbyism. we need to improve all of these things to supply enough housing for everyone.