One software developer with two jobs

A few months a ago I had a conversation with a friend. They mentioned that their colleague, a software developer, was working 2+ jobs at the same time. The professional life was split between doing 2 jobs and searching for more in case of one of them defaults. I don’t recall if I asked how is it possible to work 16 hours a day. Still, it made me think, how on Earth it’s even possible.