X-altruists are compelled to good, even when doing so makes no sense
and brings harm upon them. The cannot tolerate injustice, and go to
extreme lengths to help those who have been wronged, regardless of
their personal relationship to them. Now, I am not speaking of the guy
who helps an old lady cross the street. I am speaking of the guy who
throws himself in front of a speeding bus to push the old lady out of
the way, killing himself in the process. The average, kind, thoughtful
person does not take these kinds of extreme personal risks on a regular
basis.

If you asked someone with an X-altruistic personality why they take
the actions they do (and I have personal knowledge of at least one
person like this), they would tell you that they couldn’t help
themselves. When they are faced with that moment, they just act.
Compulsively. Barely considering any other course. The lack the impulse
control to stop themselves from doing “the right thing” when it comes
to the welfare of others, yet ironically, it almost always results in
some form of negative consequence for themselves. They have no problem
breaking the rules when it means helping an innocent, yet they highly
value the importance of obeying rules in other contexts. That’s crazy,
you say? Now you’re getting the idea. —Andrea Kuszewski

I thinks pretty much every super-villain says this to the hero at some point during a megalomaniac monologue, so it’s no surprise — still it’s interesting to read the psychological background.