Betta fighting has been around for the age of time. Seening how bettas are naturally aggressive they were used for fighting and a way of gambling.  The history of this was these bettas would be collected from the wild, trained, and used in combat.  The winners would be bred to contiune the fighting bloodline and the loser bettas would be healed and released into the wild. 

 

This pratice has been banned in some areas, but it will never go away.  Fighting blood lines are often sold for good money.