Humans are not much evolved past animals. Most connections in our brains are hardwired; trained into our ancestors thousands to millions of years ago. Most of our social behavior is tuned to living in small bands of no more than 50 people, and yet today with social media we're cohorts of millions.
You should understand that most of your insecurity comes from the size of population you're in. Being the best at something has similar odds of winning the lottery, and if you expect to win you're in for disappointment.
I have faced this inferiority problem myself, and while I don't think there is an easy cure, I know some things that help. First, cut down on internet usage, especially social media. Next, join more niche communities (<20 people), and seek to be a productive member of them. You may not be the best at Dominion online, but I guarantee you that you can find an IRL gaming group that will be impressed by your skills. It sounds silly, but being a big fish in a small pond does wonders for one's confidence.