I wonder how you teach people the necessity of humility. I'm all for being confident about something you do, especially something you deem that you are pretty good at. But, putting others down about a particular thing, whether it may be direct or indirect, is never nice and highly uncalled for. There is a difference between being confident and being arrogant and cocky. Humility. People need to know how to practise humility. I'm not saying you should tell people who sing your praises that you aren't that great when you are obviously a master of a certain art, but just don't think that you're in a position to be irreplaceable cos it's far from the truth. There is always someone out there better than who you are and what you are. It all depends on personal perception and how we all perceive certain things to be.
It's the same for every other matter isn't it? How most people generally think that they are irreplaceable in every certain way possible. Even the weight you hold in other people's lives isn't irreplaceable.