I agree with the sentiment of the comment you're responding to, but I also think this is a valid question and don't understand why your comment appears to be downvoted.
I agree with his overall sentiment too, there are lots of cases of monopolistic practices harming consumers, but I just don't see the same thing with housing prices. Low interest rate loans and restrictive zoning seems to be more of a problem than a few companies colluding together to drive up housing prices.