Actually the medical example is a pretty good corollary with software. Getting into medical school is extremely competitive, probably harder than getting a job at a top tech company. And while grades are a major part of selection, most schools also want people who spend their free time doing biochemistry research, volunteering in hospitals, running clinical trials. Then once you become a doctor, the amount of time you spend working becomes a big part of how your colleagues judge you—if you just work the minimum to keep your license, other doctors probably won't respect your skill much. The difference is that I guess doctors don't usually practice medicine "for fun" on the side.