Why try hard if you can succeed by being lazy
That's fantastic and I envy your ability to switch off,
Unfortunately some of us can't achieve that mindset.
Personally I love burning the candle at both ends and squeezing as much as I can out of my time in the quest to learn and become better at what I do.
All for that slim chance I might create something amazing - chances are I won't but at least I can pass away knowing I gave it my all rather than reaching 80 and thinking "ah but if only I tried a little harder...".
I think that's where it stems from. The insecurity of wasting time.