Just as an example I will share this little story.

In 1982 I was in the Air Force and we had just gotten our computers on the Arc Net (Thats what the internet was called when it first became avaiable). We were searching around to find out what was on it. Back then all the addresses were 7 digit numbers, no www. stuff. We accidently wound up on the main server for Oakland International Air port. We could print out a ticket to anywhere for free. When we realized where we were we shut the computer down. We were there for maybe 3 minutes. The next day (Exactly 24 hours later) 2 FBI agents were at our shop where the computer was located wanting to know who did it. No kidding. We told them what happened and that we were all in on it. We were looking for games. They told us to stop doing that and to never do it again. We agreed and then they left. That was in 1982. Now Its more than 30 years later. I cant even guess what they can do now. I just thought Id pass this little story on from my own personal experience.