It wasn't even because the guy said "nigga" or called the other guy a "nigga." He said it multiple times, ran his mouth, and basically asked for escalation in a normal everyday stand-in-line situation at a store. Then tried to kick the guy's can when it fell on the ground. "Nigga" was just the beginning of the issue, as pure provocation took over for the rest of the time.
Being drunk, high on drugs, or angry with life isn't really an excuse either. It's not hard to conduct oneself properly in public. I'm an introvert who hates himself and hates the world but I'm not out there getting in random altercations.