There is no paradox. Buying a house is more expensive than maintaining it, partly because maintenance is somewhat independent of purchase price.

I think you’re trying to say that an expensive house is more expensive to maintain than a cheap house. That’s true. But the salary required to buy any given house is higher than the salary required to maintain it, for the most part. I’m sure there are counter examples, but on the whole most people who pay off their mortgage experience a pay raise, effectively, which has been my own experience.