Then add in the Dunning-Kruger effect (the real one, not the popular misinterpretation of "you're so dumb that you think you're smart") and judging what exactly mediocre means becomes even more difficult.
But in the end, sure you can convince yourself that the negative feeling of not achieving as much as you might have been able to isn't worth losing sleep over, and you might end up 'happier'. You can also try to leverage the feeling to stop yourself from wasting those 50+ hours rewatching Game of Thrones and instead putting that time into becoming more like someone who you perceive as being less mediocre than yourself.