Today my supervisor said you cant do anything excellent.
Then I heard myself saying spontaneously: ok fine ... then do I have right to live or not?
does a mediocre deserves a dignified life or not?
Hey, my friend, your supervisor made a big mistake. Your are the best. Trust yourself. Everyone in the world will find a great job that only fits him. So, work harder, you will find your position.
Your supervisor will not win anything if you lose self-confidence. Don't care about what he says. We have a proverb here saying that the better is the enemy of the good. You don't have to be excellent to do a good job .