They're not building their own jail, they're (usually) trying to find a way they can be valuable to others.
I see it as a joke. A very good joke, as was mine when I said around that I had discovered petroleum in SL oceans and that I will make money by selling gas. New vehicles would need gas and outdate today's energyless vehicles.
Some laughed, and some were scared, saying that creating artifical scarcity was an economist's sin and that I should burn in hell for that. Then, I'm now building a full range of bathroom items, showers, tubs and toilets using water for added realism and fun. Of course you have to subscribe to my water supply company and pay me monthly for added realism and fun to your Second Life experience.
Gass-less vehicles and water-less toilets will stop working from release 1.14. I'm talking with Linden to introduce diseases, earthkaques, and floods for release 1.15. A basic earthkaque blowing all dungeons and sexballs in a sim and will cost only 300L$, so everyone can afford it. Deluxe earthkaque will damage malls and casinos in 5 sims but will be a bit more expensive. It will boost SL's economy to unprecedented levels.
Next secret plan is war.
