How much do you make with investment properties?

My dad bought his first non resident investment property 16 years ago and it is 80% paid off, with the money we collect in rent every month but when our old tenant committed suicide, he rented our our apartment to a new tenant for $800 more than what he charged the previous tenant so now we are earning our investment money back faster and if we sell it, that's even more profit. Now he has other investment properties too. The house we live in might be worth over 5 times what we paid for it 19 years ago but houses increase in value faster than apartment buildings.

How much do you make with investment properties?
Post Opinion