I’m confused

Hello humans of the internet! Im going to tell this story because honestly I’m so confused. I don’t know what was going on.

I was on the grocery store at 9AM. That’s 9 in the morning. And this huge angry man walked up to me got in my face and aggressively shouted “I said hey.”

I really don’t think this man said hey to me. I know I don’t hear super well, but he just walked at me and shouted. I’d never met him before. I was just trying to get some allergy medicine at 9 o’clock in the morning. So, I looked him in the eye and said “good morning” as nicely as I could. He paused briefly then got in my face again and said “smile when I say hey. Answer people.” So I ducked down a random aisle and did my best to disappear, then quickly left the store. I didn’t even get everything I need and will have to go back to the store tomorrow.

Why is he like that? Why would a person feel they have the right to get in a stranger’s face and demand their positive attention. I think I’m a generally nice person, but I’m not going to smile at you when you’re yelling at me.