Sure, but these people aren't seeing their wealth erased. If anything, there'll be a discount of say 10-30%, probably realised over a period of 20 years, and there's a good chance the only effect it will have is that prices stop rising faster than income, but will rather stay stable. i.e., making it more affordable, without them losing any money.
If that's the price that has to be paid, I think there's no moral argument to be made on this discussion, what remains is a legal-political challenge.
Finally, I do believe this is all part of investing into the housing market. If you want a risk-free investment, choose government bonds. If you want to play the housing game, this is part of the story. You can't expect to invest a few million into an overpriced industry with a scarcity-controversy, and expect to reap risk-free rewards. Everyone who buys a house in these areas knows that your money pouring in and your legal defences are inadvertently screwing with housing affordability. If you're okay with that and want to make a risky investment, so be it. But then don't treat it like some kind of safe retirement plan you worked your entire life towards, it's not.