This is a reaction that I had for a time, until realizing that outside of just "some people are different", there is also the wider protestant work ethic putting work at the center of their life, and assigning a moral value to productive work.

I'm describing it in too vague terms to be appropriate, and most people might be thinking it in that way, but I genuinely think there's a part of it in a lot of the "I did this paid service as a weekend project" mentality.