A few of the massively supported teams i
n Europe in places like Naples and Paris have numerous hooligan groups who don’t get on with each other. Their supports are gigantic.
Sometimes it stems from disputes within the same firm where splinter firms form, sometimes with different firms wanting to takeover a part of the stadium that another firm occupies, sometimes linked to opposing street gangs outside football, to different political ideologies. Sometimes the rivalries go back decades.
Paris Saint Germain have loads of different ultras and hooligan firms, many of which don’t get on with each other.