Some of those places you listed crashed hard after 2008 and others didn’t. I think there are trends in vacation destinations that can cause speculation. Also, many of the the buyers are leveraging wealth from equities that is more variable than the salaries the average homeowner uses. If there’s a prolonged stock market drop during a recession, many may be forced to liquidate when buyers are fewer and poorer (you’d prefer not to sell anything in a downturn, but the vacation home might be the first to go). I saw people take huge losses on vacation properties after 2008.