More straightforward is the theory that implies that they started as goons (gabellotti) providing security to wealthy landowners.
This is the real origin,all the serious historician writers say that the mafia started as the gabelotti to control the peasants and that after the WWII the mob in the cities especially in Palermo made the jump to street racket to construction racket,the waste bussiness and made political link to politicians thanks to the votes that they controlled in their zones.
The other hypothesis are just fantasy.
