Work and fun are two distinctly different beasts altogeather.
However, if yeu have too much emphasis on work, then yeu associate fun with work, and no longer want fun.
Yeur example above... too much dealing with stupid people at work, makes it so yeu don't want to deal with ANYONE for fun because yeu associate it with work.
It's generally temporary, and it also means that line of work is unhealthy for yeu. I'd highly suggest looking into a new line of work quickly, because once yeu go down that road, yeu'll be stressed out constantly with no relaxation point, and will eventually stop caring about people at work too, and likely get fired/laid off. Working with people isn't so much the problem, as is working with ABUSIVE people.
And unfortunately, the sales and services section of our culture, has somehow become an accepted target for abuse, where it's perfectly alright to scream and yell at someone for yeur own mistake, but they have to take it because they work in a store.
Get out while yeu can, yeu are already showing that this kind of line of work is not one yeu excel in, it will cause yeu no end of grief, and the longer yeu say, the more long term its' effects shall become. Look for a line of work where yeu can interact with people, but on a professional level primarily. The service industry is just not suitable for some of us, even if we really like dealing with people.