In monster hunter, the speedrunning community is migrating to PC because the ability to use cheats to negate the huge amount of RNG present in the game. Cheating is usually looked down on by speedrunners for obvious reasons but because of the difficulty of speedrunning a game with so much RNG(not rng that effects your gameplay, but that effects your ability to play at all), modders are basically making a new game with the rng removed and people are speedrunning that, and it's widely accepted as necessary by the community.
So cheating is often just a means of either getting something new out of a game or 'fixing' aspects of a game that the community takes issue with.
I agree that players like you describe, who's main goal is griefing other players, also make up a large portion of cheaters, just wanted to further elaborate on your response that not all cheaters are doing it to 'move up the leaderboard'
I also excluded professional players because the original poster was basically trying to get an answer regarding what kind of person would cheat when there was no extra incentive. Obviously, professional players or players in any games that offer valuable prizes have a real incentive to cheat.
First, these are not great lengths when all you need to do is download and install an application.
Second, some people don't get as much kick from playing a game as from dominating other players. They want to win the game in any way possible, but don't consider winning fairly to be any more satisfying than winning with cheating. They might be in denial over their abilities and use cheating to feel better. They don't feel any need to be courteous or fair. These are people who, when they loose a game against you, will say "fuck you" instead of congratulating you.
Don't try to find logic where there isn't any.