I’m not really following you. The mortgage is just you paying back the money you borrowed to buy the place.
Are you expecting that owning property should incur no ongoing cost?
By the way, your example mortgage has X number of $1012 monthly payments, and then a final $540,000 payment. That’s why it “costs less” than your taxes/insurance/maintenance.
The parent is saying that the monthly taxes and other costs are greater than the interest on the mortgage. So the idea that you've "paid off" your house provides a false sense of security: it will continue to have significant carrying costs.
Are you expecting that owning property should incur no ongoing cost?
By the way, your example mortgage has X number of $1012 monthly payments, and then a final $540,000 payment. That’s why it “costs less” than your taxes/insurance/maintenance.