Good question--
Here is my answer--
1. I will pay a significant amount of long term capital gains tax reducing the amount I have to reinvest (I don't qualify for 1031 exchange).
2. There are fairly significant closing costs both on the selling, buying and borrowing sides.
3. The amount of time involved in selling then buying again is significant, especially if you are coming from afar.
4. We looked for a long time and finally decided to build because we couldn't find a resale home we really liked. If I knew I could repurchase my current house, this might be an option.
5. I bought long enough ago that prices would have to fall over 50%, and stay there, for me to be in the red.
6. I can afford the home we have even if things go south and interest rates rise.
7. We REALLY like our home and the area.
For all of those reasons, I am only going to sell if I can get a price that makes it worth it to sell. I'll then take the money and build another home sometime down the road.
If I don't sell, no big deal. We didn't buy the home as an investment. We bought it as a place for us and our kids to build memories. But, if we get lucky (I did not buy the house thinking prices would skyrocket) and the house commands a large enough price, I'll take the money and go on some really nice memory building vacations off the interest I will earn on the gain. For me, I see no real downside either way.