My parents bought their house in 1998 for 75k in Sandy San Diego near downtown. I bought mine in 2005 for 500k near sandy San Diego. I then bought a second place for 475k up in Irvine. All were 3 bedrooms, two bathrooms. The first two houses were from the1920s. The last one made in the 80's. I hope that makes it clear. I sold my California homes and moved to rainy Seattle and was lucky to find a house for 550k in 2019. I left the California market when the Seattle market started getting too crazy too. In just these 5 years the price of my old homes according to Zillow has gone past the 1 million mark. One is 1.2 million, the other is 1.1mil. imagine that! In 5 years there's no fuckin way I could just rebuy my old houses. So for anyone out there trying to move, do what I did and save first, buy before selling, and calculate for the worse possible outcome. That will get you a realistic baseline... think of everyone involved as little fucking money sharks, the contractor 10k, the buying agent, 30k, the bank 30k, etc etc.

If you sell, your run the real risk that your entry money goes stale and you'll be unable to afford the house you used to live in.

Exactly. Auto loans are relatively short-term, and you're probably more likely to default relatively early into the loan than later, esp. since you would no longer be upside-down later on.