It is kind of a toss up here. If you are curious about the world around you or like to explore, you probably want to know what makes a system tick. If you want to impress friends or look "cool", then you destroy things or leave your mark. It depends on the motive. Just because someone breaks into your computer and it appears they didn't mess with a file, it doesn't mean they didn't. Many hackers know how to change certain entries in a system's log, or file timestamps. Just make sure you have a good firewall and updated antivirus software. What has happened to you can happen to anyone.