I've found a mixed approach helpful: spend some time with people who don't know how to do X, because you can add a lot of value to their lives by showing them how to do it better. Spend some time with people who are much better at X than you, so you consistently improve (and have new things to teach.)

I think most people tend to be far too hesitant to teach things they know, because they know that someone else understands it better. But if that person isn't doing the work to teach, then simply talking about what you know can be incredibly valuable.