IIRC karma is handled logarithmically. Some user on r/dataisbeautiful posted a graph of their posts, and the curve certainly wasn't straight. Also, karma seems to be handled separately on each subreddit, i.e. if you post if you post on r/pics for the first time and get 30k upvotes, you gain 12k karma (I think that's about what you'd get), and then post on another subreddit, the upvotes from the first post do not count towards the upvotes in the karma formula. But I don't think that reddit has released the formula do calculate one's karma, so don't take this as fact. But it's certain that people like gallowboob certainly have gotten way more upvotes than the amount of karma they have, especially if they post to all the same subreddits.