Say the home-buyer can just barely afford the mortgage payments and their renting alter ego can just barely afford rent. Then necessarily the renter is getting

Say the home-buyer can just barely afford the mortgage payments and their renting alter ego can just barely afford rent. Then necessarily the renter is getting a much nicer place. Holding the niceness of the place constant, the renter will indeed have extra money to invest just like the home-buyer is gradually building equity (investing) in the house. Rent ratios are actually often such that the above is even more extreme: buying a house cost more per month even if you pay only the interest on your mortgage (which is equivalent to renting: building no equity in the actual house).