[z2]

Jokes aside, I think that's exactly it. Mathematicians aren't tempted in the way that others may be in connecting what they do to humanity. Not being in it to cure a disease, build a better mousetrap, or create a triumphant explanation for existence does wonders to keep the ego in check.

[curuinor]

Difficulty of mathematics and the fact that they can be wrong can also keep ego in check.