Another person I know had a full-time job with a housing allowance (the job covered his housing). Rather than just wasting the extra money, he decided to be disciplined with his budget and save what he would have spent on a house payment for a down payment on a rental house. After purchasing his first rental home, he continued saving his housing allowance and putting it toward additional rental properties.
20 years later, he retired from his job with 20 rental properties—all of which were paid for. Between all the rental properties, he was probably getting $15,000 a month in free cash flow on top of his retirement.
Today, this man helps his tenants get on a budget, become financially disciplined, and buy their own homes. He has owner-financed multiple properties to help people buy houses and considers it his personal ministry to help his tenants in this way. He is a mentor and coach to many tenants and is someone I have looked up to for a long time.