Am I being delusional?

I am just starting as a landlord. I plan to start out with mobile homes or maybe duplexes, then make my way up to single-family houses, then large apartment complexes and even more. Maybe even commercial real estate. In my current state of mind, as long as I can make more in rent than what it costs me for the loan and the maintenance of the building and taxes, then I should be good. I am limited by the amount of loan I can take out. I know people personally who have done things similar to this. They started out renting on house, now they own at least 10 and they make a profit off every one.