Members of the shadowy but media-savvy hacking collective Lulz Security, or LulzSec, announced their group's dissolution on Saturday, in a Twitter message to 280,000 followers. In their 50 days of activity, the publicity-seeking group had successfully hacked the websites of the CIA, the U.S. Senate, Britain's Serious Organized Crime Agency, Sony, PBS, and other high-profile targets. And while LulzSec came to embrace politically motivated hacking, they also hacked sites and disseminated stolen information just for the "lulz," or laughs. If it was so much fun, why did LulzSec suddenly and mysteriously disappear? Here, four theories:

1. The law was closing in
Like any good band, the "rockstar hackers" of LulzSec suggest they wanted to "end things on a high note," says Parmy Olson at Forbes. But "the looming threat of arrest" was probably the big reason they called it quits. Britain's detention last week of alleged LulzSec collaborator Ryan Cleary reminded the hackers of "the dangerous waters they were treading in" by hacking the CIA, an FBI affiliate, and Arizona's police database. Cleary's arrest clearly "shook the group," says Joseph Menn at the Financial Times. Hacking experts have "serious doubts that Lulz was going out on its own terms."

2. They were just bored
One member of LulzSec told the Associated Press on Sunday that the group isn't "quitting because we're afraid of law enforcement," but rather because "the press are getting bored of us, and we're getting bored of us." It's possible that LulzSec's members just "didn't care anymore," says David Murphy at PC Magazine. But "that seems like a strange explanation on its face," given LulzSec's well-established love of the spotlight.

3. They picked disastrous fights with rival hacker groups
LulzSec was popular with the media and on Twitter, thanks to well-regarded spokesman "Topiary," but the group was hated by other hackers, many of whom it engaged in high-profile spats. Some, like lone-wolf ex-military hacker The Jester and rival hacking collective Team Poison, were relentlessly trying to uncover the real names and other personal data of LulzSec members, and claimed they had the goods. LulzSec probably felt the net tightening, say Charles Arthur and Josh Halliday at Britain's Guardian. "And once their secret identities are out in the open, it's game over."

4. They'd run out of ideas
There's a limit to the number of low-hanging targets that a small group of LulzSec's skill level could take down, says Charles Arthur at The Guardian. "LulzSec was running out of fuel," but the public and media wanted "greater-ever acts." In the end, disbanding was "the obvious, safest move."