How can you possibly feel mediocre? Against what? You are a completely unique individual. There is no one like you in the entire universe. You have a blend of skills and traits no one else possesses.

What are these abilities and insights you have that no one else has? It's up to you to uncover them. That takes some work. It also requires that you listen to yourself for a change rather than other people. It may require further experimentation, but you are the best in the world at something.

Get off HN and find out what it is.

One more thing: watch the self-talk. Be proactive and solution-based. Your thinking should be where your problem isn't.