One thing I've noticed is that people's XP contributions are definitely weighted differently.
So, for example, I think as a non-community-member I grant 1 point per "XP" that I give. I think community members grant more, and I'm wondering if mods grant even more. There's probably other ways to increase this, like participating in the site more - have more friends, follow it on twitter, buy stuff, I dunno. It lists it as "reputation power" so who knows. Maybe it's listed somewhere?
Cleverusername only got contributions from 10 people, but his point total is 58. I know at least one is a long-time mod and I'm guessing the others are just people who are also weighted more heavily. By contrast, I think I've gotten XP maybe 25 times or so (not sure how you can tell once it's over 20 times), and I'm just at 79 points. And frankly even that is skewed, because one time I randomly got XP from Morrus (no idea why) and it bumped me up more than a full level, I believe (like from 4 to 6 or something like that). I'd guess his one-time XP was maybe 20 points or something along those lines.
Plus, XP is probably still being messed with (especially as all these subscription services keep changing) and it only started ~1 1/2 years ago or so anyway so it really doesn't mean very much. People who have been on these boards FOREVER are like level 3 and then there are some new folks who are above them (case in point).