BAN-TUN is a formerly successful colony world that has suffered badly from overproduction and callous mistreatment of its environment.  As gainful employment has fallen, the number of violent gangs has risen.  The immensely wealthy barons who rule Ban-Tun could easily emigrate elsewhere, but no other nearby planet has such a desperate population willing to do almost anything for money.  So they stay and import off-world luxuries, while hiring the gangs to fight each other for their amusement.  Gambling is common on Ban-Tun, but the odds on its long-term survival are very long indeed.