It also hurts when they're younger, and have been doing it for less time than you. I'm a purple belt in BJJ, and have trained with people competing at a high-level that were basically small children when I started, and have done it for half the time I've been in the sport.

Pair that with working with several accomplished engineers at work that outlevel me, despite me graduating before they even went to university, and sometimes it's easy to feel a bit shit.