How do hackers effect video games

Mostly Hackers don't do much with the video games, although they do rip graphics and text (ripping is illegal) as well as hunt for glitches and cheat codes, but they spend most of their time modding the systems so that they can run home brew video games on them as well as run other programs. The problem is that game companies are always trying to keep their systems from being hacked into so that they can't be modded. The hacker side is that once I buy a system it is mine to do with what I want, and if I want to mod it I can because it is my system, not yours.