Thinking about this more, maybe the solution is not to detach self-esteem from skill mastery, but to find a better yardstick to measure skill mastery than our peers' skill level.

Given that all skills are used to achieve an objective, we can measure mastery of a skill by looking at how effectively we are achieving the objective. e.g. I am good at programming because it used to take me hours to solve task A, and now I can solve it in minutes.