I met someone like that at a party over the weekend. She bought her house in east Oceanside in 2005, paid an outrageous amount, and thinks that it will be “back up in 5 years” to that astronomical figure (it’s dropped at least 40% since 2005, I found out later). She has also convinced herself that property on the coast hasn’t gone down and won’t go down.
It’s not surprising that some people are in denial – it’s easier than admitting to a monumental mistake. Pointing out the facts just makes them defensive and even hostile, so I don’t bother.