Why do people cheat?

Using engines means that the engine won the game and the cheater is simply the assistant - like the page turner in piano music. If impressing people you know only from online with your fake rating means something to you, you should seek mental health.
I had to work HARD, at age 66 last year, to return to chess after years away and play decent games. I'm very proud of 1800+ but would be proud of 1500, 1200, wherever my skill would place me. That's MY result, not an engine. In fact, my rating took a hit last Fall and Winter because I was trying out new attacking philosophies and openings and it took a while to find the right amount of aggression, overprotection, etc. But I had FUN - and that's what people should be after rather than a rating!
Cheating disgusts me in all forms but it absolutely amazes me when the game is online for no prize!
I was a USCF Tournament Director and ran high school Swiss System Tournaments where there were 30-70 players and usually 14 trophies. I had to keep an eye out because players would cheat for those trophies - especially against unrated players. Engines, hidden on cell phones, were not the only way they tried to cheat.
One trick was to pick up a piece of his that his opponent had already captured and tap it gently on the side of the board, playing with it until the newbie looked away, when he would place the piece on the board, the newbie usually being nervous and inexperienced enough to not notice the move.
Another trick, which the USCF rules unfortunately force TD's to allow to occur, is when a player forgets to hit the clock after his move and his opponent pretends to be in deep thought for a long time so his opponent's clock will run far down or out of time.

Some probably do it just to punk out others. Some probably do it just to see if they can get away with it.

Much the same reasons as in Politics, Olympics, Business, and Marriage.
Winners are grinners.
So they say.
Cheating is unfortunately very common in fallen man.
But, Chess is such a Noble Game that it should never happen, should it.

I did it once about 3 years ago. Before the first move, opponent messaged that he/she was going to beat my ass and I was going down. I'd always been curious to how it would go with a Chess engine so I thought then was as good a time as any!
To be honest it is not overly difficult to tell if someone is using an engine, especially if they have a low to medium rating.
I've never seen it myself, but I've heard complaints. My question is that since the ratings have NOTHING to do with actual strength, why do people cheat to gain fake rating points?