Well it started off as fun and challenging but it eventually became ridiculous. (Very much like real life in my opinion

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I think there were mainly two reasons why it all stopped.
The original game hackers did it for fun, not only was it challenging, it was also rewarding when you succeeded. You could upgrade everything instantly for free.
The games were originally hacked because of the intellectual challenge and also to avoid paying money to the game. I don't believe the games were originally hacked to make money, they were hacked to save you from spending money.
Unfortunately everything changed when players started selling these hacks for money. Some wouldn't even bother changing the name on the hack, they would just take the hack from here for free and sell it elsewhere on the internet, too many hackers started using these hacks on legitimate players who payed real money for upgrades in the game.
Eventually the game developers had enough complaints and noticed they were losing money so they finally updated security on the game and made it much harder to hack.
The game hackers went underground to private forums, took some selected users with them and continued to find new hacks and release them, but these hacks kept appearing on the other forums for sale.
It got to the point where developers could patch the games quicker than we could find hacks...........They must have infiltrated the private forums because i remember it getting to the point where they started patching things in the game we were discussing on the forum before we had even hacked it yet. Either that or mind readers really do exist