Yup. Physically fighting anyone as an adult in a society is maybe one of the stupidest things in the world. Comes in second to actually picking or starting said physical confrontation in the first place.
Agreed but I'd say it was a distant second. There is no time in my life where I would have behaved like either party involved in this incident but if this guy was verbally abused, drenched with a beverage and then sneak-attacked after being told it was over, I can understand his reaction. At least up until the post-beating celebration.