I have a friend that lives in a 12 million dollar house -- he started (years ago) buying and fixing up single family rentals - while he and his wife owned and operated a restaurant. They worked their asses off late nights and burning the candle at both ends... After awhile they worked into duplexes and fourplexs...
Now they own HUNDREDS of apartment units - most in a the LLC style - where "investors" buy shares and get semi-annual interest payments - the investors all together own 49% and Ray owns 51% plus gets management fees etc.
The problem for "most" buying this type of property -- they don't have the skills or time to do the work themselves. That really complicates things -- or adds to the cost basis if you have to pay a pro - but LONG TERM - this is a great way to build wealth and cash flow. Pound that profit back into the next project - or pay off a couple early (20 years instead of 30) and you've got instant retirement savings and income.