Could it be possible that when these sellers originally bought the properties, they were told by their Realtors and developers "Now's a great time to buy; they're not making any more land; buy before you're priced out of the market; this area is "special" and worth these high premiums; the baby boomers are coming! the baby boomers are coming!!!; real estate values only go up; if you don't buy now you'll regret it; real estate investing is less risky than the stock market;..etc., etc., etc." ??
If the seller is now finding out what their Realtor/developer told them wasn't exactly factual on the way up, I can understand why they're having a difficult time believing what they're being told on the way down.
When it's all said and done, all the rah-rah Real Estate rhetoric spewed by the NAR/FAR, their agents and developers during the frenzy is a contributor what's biting them in the arse now.
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You're making a very good statement about why Realtors should never make forward thinking statements about values when they are representing a buyer. That type of talk is better left for people both trained and insured for that business.
In 2004 and 2005 I watched to me professionals tell a buyer that they will make money in a transaction. IMO, thoses Realtors should buy the properties back now.