Why do people DDOS other people?

srsly, I just tried to get onto Xbox live, and it wasn't working, so I checked online and "Lizard Squad," a group of hackers, has taken down PS4 network and Xbox live. They did they same thing to LoL and WoW in august.

Why?

Do people find enjoyment in taking away other people's avenues of fun? The same goes for people or DDOS enemy players in League. Is it fun to win a 4v5 or 3v5 when you forced the enemy out of the match so that you could have an unfair advantage.

I hate a lot of people, but no one compares to the amount that I hackers, just for the simply that other people do things for a reason, whereas these hackers do this just for the simple fact that "i can"