On the other hand; would you personally make that choice if you were in their situation? I am willing to bet you, nor any other reader, would not. While that doesn't excuse the greed aspect of it; it does cast at least some light upon why they are refusing to sell and take a loss on it.
If you only paid $100,000 and you made $1,000,000; you'd have $900,000 profit; of which you'd probably only see ~60% to ~40% of, if Capital Gains taxes are anything near what I think they are. If we assume a "worst case", where the Federal Government takes 40% and the State takes about 20% more, that means your tidy profit is only about $390,000. That means you've probably got to secure another $140,000 in financing on average to pick up a more modest $500,000 home (in today's market) to retire in.
But villainizing the boomers isn't going to solve the housing crisis easier either. We legitimately need more homes. We. Need. Them. Yesterday. So maybe the policy needs to lean towards bigger developments that cost less. We did it during WW2; where massive amounts of homes were built cheaply. We probably need to achieve that again, and do better than we did during a war that was diverting supplies away from the effort.