If you are selling AND buying, timing is very important
If all you want to do is to change for another house (without losing any money), then the state of the real estate market really isn’t an issue… The real estate market could be going up or down, it doesn’t matter… As long as you sell and buy as fast as possible… at the same market level.
For example, if the market is going down, then the average house price is going down.
When to buy or sell a house
But if you sell your house and buy a new house AT THE SAME MOMENT, your average house value stays the same.
However, if you sell when the average house price is going down, and you buy when the market is lower than when you sold your house… you make a good investment because you are buying at a lower price.
If you do the opposite, i.e. sell when the market is low and buy after the market has risen, you lose… because you are buying less with more money.