A financially independent social worker says his sober-living rentals return up to 75% on his cash. Here's how the niche strategy works.

As a social worker, Scott Steenbergh never seemed to be able to clock out.

"The hours were always tough," the Michigan-based investor and father of two told Business Insider. "It seemed like, no matter what, I was always required to work in the evenings, work on weekends. People were obviously in crisis, and I want to help, but I also wanted to be able to be present with my kids."

Real estate investing seemed like a possible path to more time freedom...