why do people hack?

Hacking doesn't mean always something bad , lets say you bought a car and you don't like it's stock headlight , so you go and buy custom headlights , this is called HACKING

I admit that some hackers are annoying but some hacks are useful, fun and can extend the life of a game

I'd say that people use cheats just to have "fun" in a way - a way to always dominate and get attention.

because its funny to see other people crying every round

I would say to get free things with out work, same reason why people steal.

i used to have a rgh but i was good at games legit, it was sometimes fun

Cheating can be fun to mess with people, I know it's fucked up and can ruin the fun for others. But sometimes you hit a peak of skill in the game your playing and maybe want to do other things in the game to entertain yourself, after all it's a video game.

Cheating in games can sometimes lead to popularity and in some cases money. If you dupe items on a game and then sell them, you're profiting.

Unfortunately, there are many people who are extremely selfish, greedy, etc. Luckily, there's more white hat hackers than black hats. (I think so, at least.)

So they can get an advantage so they can get enjoyment