I sold for multiple reasons (just recently closed escrow):
1. Pocket $500K Tax Free. The goal would be to do this multiple times over the coming decades, as long as the tax code allows it. This tax loophole is unbelievable and just to tempting not to take advantage of it at the top of the market.
2. To move into a better area and nicer home (better schools).
3. When the real estate market is depreciating, it makes perfect sense not to own (renting is a far better deal). This is easily seen by playing with a good buy vs. rent calculator.