Max Levchin phrased this very point beautifully on his Startup School talk (I think it was an advice by Peter Thiel): "A difficult problem doesn't necessarily m

Max Levchin phrased this very point beautifully on his Startup School talk (I think it was an advice by Peter Thiel): "A difficult problem doesn't necessarily mean a valuable problem". Your job as a programmer is to add value. Now if you keep working on super interesting stuff, that doesn't add value, what's the point really? You should spend your free time on the interesting problems that don't add value.