I had a buddy who kept one. He had to constantly entertain it or it would make noise that would put a school of pistol shrimp to shame! They also need constant tank upgrades to keep them happy. Sadly, my buddy came home one day after a long day at work to find that it had gotten out of the tank and left.
It took all of the corals, rock, skimmers ect. He was left alone with an empty box of salty water.
It didn't end there.
He now also pays support for the fry through a government program.