I pay $2500/mo to rent a house that was purchased for $280k in 2015 and is now worth about $550k. That's comparable rent to what I would pay for a decently desirable 2bd apartment.

Property taxes county + city are about $4300 per year. They have increased recently, and so has the rent.

If they owner put down a 10% down payment, I estimate their total monthly payment for mortgage + taxes + insurance is about $2000, and will likely remain in that ballpark.

That means rent is currently paying the entire mortage/tax/ins plus $6k per year. At the end of their mortgage that monthly cost drops to about $700, and they will own an asset likely worth $500k+.