The sellers of the homes only benefited until the bubble burst. Then they were left holding inflated property worth 1/2 to 1/3 of what they had paid for it.
If there had been some way to bet on the short market, you could have made a fortune. A blind man could see that the market was grossly inflated, just like the fake stock market during the so-called internet bubble.
I'm not sure how often that was the case, but keep in mind that in the mid-2000s the "seller" was often a residential homebuilder who was putting up cheaply-built houses as fast as he could, and walking away with the proceeds of the sale after paying his expenses.