It might be that the attitude comes, not from actually thinking "my stuff doesn't matter at all", but more from thinking "if I leave, almost anybody else could

It might be that the attitude comes, not from actually thinking "my stuff doesn't matter at all", but more from thinking "if I leave, almost anybody else could do my job". Not sure if this was the case, but I believe a lot of our developer egos would like us to think that I and ONLY I would be able to do this particular thing (even if you know you'll actually never be THE ONLY one at anything) it definitely feels like you might be one of the very few. And then when you realize that no, you are not a special snowflake, you kind of feel "my contribution doesn't matter", not in that it doesn't actually matter at all, but in that someone else could've done it as well.