Because they aren't offered insults nearly as often.
"What I generally find people saying when they say “I guess I’m not easily offended” is actually closer to “I don’t actually have that many people who offend me.”
In general, what these dudes are actually saying is “Ninety-time times out of a hundred, people acknowledge and support me, and I quietly assume that as my birthright. And that hundredth time someone doesn’t acknowledge me, well, that means I’m not easily offended!”
Yes, this seems obvious. But I hadn't put it together in exactly this simple, straight forward way. This article reminded me of something else that should have been obvious but I just hadn't thought of until I read it. Did you know that straight, white male children are the only ones, as a a group, whose self-esteem goes up after watching television?