system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is the motivation for these hacker groups to keep taking down the Xbox live and the Playstation network?
gpt
As many hacker groups put it, they usually do it "for the lulz".

In other words, they get a kick out of (pleasure/enjoyment from) causing destruction, chaos, and/or inconvenience to many people. 

It satisfies their need for attention and to feel important -- as though they have accomplished something great (not great as in good, but rather great in the sense that it has a significant impact on people).

It's a similar reason why some people develop viruses that provide no monetary benefit to the developer (ones which merely cause significant annoyance or inconvenience for users that have been infected).

Sometimes these attacks are targeted though in the sense that they are motivated by certain ideologies or political beliefs (e.g. maybe the hacker/group views Microsoft or Sony as the enemy because they are doing something [or have done something] the hacker/group doesn't agree with).