Being a mediocre professional is great! Do you complain when the guy cooking your meal at a restaurant is a mediocre restaurant cook? Or when the doctor prescribing your medicine is a mediocre doctor?

Anyone who is mediocre in their profession should still feel pride in what they do. Are you among the best? Maybe not, but you are good enough that people value what you do and that is what matters the most. If you find yourself in a position where nobody values what you do then you have a problem and need to fix it as soon as possible. But in that situation you aren't mediocre, instead your main goal will be to work hard so that you can become mediocre.