I remember being very enthusiastic about helping people on, say, Stack Overflow. It didn’t take much extra effort to be nice and made me happy.

But I also burned out relatively quickly. I’d happily answer new questions nicely, but the third or fourth time I saw the same question I spent much less effort to give a welcoming answer than I had the first time I saw it.

Of course, getting the same question repeatedly may suggest something should be redesigned.

I don’t know any good way to keep helpful volunteers helpful for a long time. The best idea I have is constantly recruiting new experts to continually replace the ones that burn out and chase off newbies.