People that announce that they're never shopping somewhere again, why?

Like, ive worked in customer serve for around 5 years now, ive seen this happen so many times and I just dont get it, us employees could literally not care any less, we forget about you within five minutes of you making that announcement and storming out. Every place ive worked gets enough customers that you as an individual never returning doesn't even leave a dent in our profits, half the time even the managers are like, good ridence, and usually the things your angry about seem ridiculous to us. I can't return something you bought 6+ months ago because I could get in trouble or even fired over it. I can't sell you that item because its not in stock. Im sorry I don't know about gun laws but im not a gun person, I work in returns and licenses, go to the gun department with your questions. Im sorry we couldn't pick up the phone when you called but do you see the lines? Im sorry there's no one in the camping department but we are short staffed and currebtl6 have one Singular employee that specializes in that and he does occasionally need days off. Just leave and dont come back if your unhappy, we dont actually care, we literally just work here.