What gives your parents more right to live there than anyone else? Just because they were born first? What about the people that will pioneer the next generation of technology? You’re not entitled to live where you want just because you set up shop there first. This is one of the fundamental reasons property taxes exist. Otherwise, most of the land in the US would be squatted on by powerful families of centuries past. If your parents don’t want to be priced out of the market, maybe they should vote for more and denser housing that would drive property prices down. You don’t get to have a farm in midtown Manhattan. Things change.