Even if it did, upgrading proportionally went up, too. Let's say that $40K house went to $100K. But the $100K house that OP originally wanted to upgrade to is now $225K. The difference between what they have and what they want doubled, and so did the mortgage payment.

Source: the many times my spouse and I have done this exercise.

Yes, but not having a mortgage is huge. And it's a giant leap from the 90k my house is currently valued at to the $299-350k that a comparable home in a metro area would fetch (I live in the middle of nowhere).