If they were equally qualified they would still demand a comparable salary. A full stack dev in Houston makes nearly as much as one in SF with the same qualifications.
I understand that this is just a single anecdote but I work with quite a few people who have moved here from SF – and have friends who have made the opposite move – and they have all reported something similar.
If you meant "overall net income", then the Houston dev would likely come out ahead after taxes and rent/mortgage.
Plus, you get to be out in the sticks, not cheek by jowl with a million other people.