> If someone builds an expensive condo, yes this increases supply of housing in the area, but in the event that prices increase all over the place due to cartel

> If someone builds an expensive condo, yes this increases supply of housing in the area, but in the event that prices increase all over the place due to cartel-like behavior Umm, no. Adding a new expensive housing to a market does not increase the demand for existing inexpensive housing. It can have the effect of reducing the demand for other expensive housing, as in "why should I pay a lot of money for old?"