They can access otherwise hidden electronic information and copy and/or steal it for publishing. If people can do that, people can also wipe documents and other data owned by other people via the Internet. This may be considered illegal activity, but I don't care if all I'm going is getting rid of a big crock of stuff.
Oh, wait. Haha, I get it!
You've been trolling me this whole time. Ok, you got me good. I thought you were serious this whole time, but nobody can be so stupid as to think...
1. They can hack a website without any previous hacking experience.
2. Expect that website to stay down forever after being hacked.
3. Expect that website to not just put everything back up after getting hacked.
4. Expect that website to not just patch the vulnerability after it's been used.
5. Expect the website owners to not sue the guy into oblivion if they tried to hack them again.
Haha, oh man. You got me pretty good. You are a pretty good troll!