NY has not been putting up housing at an insane rate. Housing in NY is actually being constructed at one of the lowest rates in the last century. Adjusted for business cycles (we're in a peak now), NY is building less housing than they have build in ~100 years, and Manhattan is at its lowest density since the 1890s. The current period is only a "boom" relative to 2009-2012 when basically no new housing was constructed.