A personal comment: for 30 years I lived in a district of Krakow occupied by two gangs of football hooligans.
They were the scum that I despise most: feeling strong only in a group, aggressive, randomly vandalising things, involved in occasional killings, trading amphetamine and steroid, then going to church on Sunday and posing as proper patriots.
Being practically identical in their retardedness, they however perceived each other as the absolute opposite and evil. Tribalism sucks...