There are cockerels and adult roosters who spend their time paying attention to their flockmates, and watching out for predators, and that's what should be happening.
Then there are idiots who would rather spend time stalking and attacking the giants who bring food every day, and that's just not what they should be doing. This behavior is both (mostly) genetic, and then somewhat a management issue, often not fixable.
The fighting bird people selected for extreme intraspecies aggression (cock fighting!) and no human aggression, and so that's how those birds mostly behave. Genetics!
Some breeds of chickens tend to have a higher % of human aggressive roosters than others, but it's still up to the individual cockerel; there are no doubt very sweet hatchery RIR roosters, and horrible Favorelles, but the trend is opposite. Nice Favorelles, for example, and nasty RIRs.
Parentage matters! Selecting for the temperament desired in breeding stock shows in offspring, not 100%, but it does show.
Mary