Side projects are the only reason I'm able to continue working professionally precisely because they are not work. Everything about them is different from work. Programming is a great hobby and in my experience turning it into your job destroys it as a hobby. Working on a side project is to find a new avenue for programming as a hobby, so they you can continue programming for money because that's the most feasible way to make money as a programmer, but can also program freely without project managers, conflicting requirements, deadlines, slow/non-communicative/differently-visioned colleagues/customers/bosses on your side projects.