Careless minds curse.
Example: recently, at the end of a shift, I kept my ears open for instances of profanity amongst my colleagues. In a five minute period, I lost count. But more interesting than the frequency was the context of their use. Expletives were mostly used to emphasise a point or demonstrate strong emotion. “What a twat.” “I can’t believe this shit.” “That’s fucking hilarious.”
See, falling back on curse words is a shortcut. It’s easier to swear than it is to use language, tone, volume, tempo and non-verbal signals to drive a point home. It’s easier to preface a verb or adjective with a curse than it is to search for a more suitable, single word. Thus, to curse requires less effort than to think before you speak. That’s why cursing is more prevalent amongst “blue collar” workers; they care less about their words than their “white collar” counterparts. They consider the propriety of language of little importance, so they allocate it few resources.
And note that I didn’t say “stupid minds curse”. No, some of the people I’ve met who use curses as frequently as “I”, “the” and “but” are way more intelligent than many “smart” people I’ve met.