Swearing

Why do people swear? All words in every language were, long ago (or not so long ago) made up, by people, like us. So who is the idiot who made up these words, why did everyone use them and still use them now? How would someone even think of something like that? And why do adults swear and then not expect their kids or children around them not to use them and punish them if they do. And why would it be a good thing by not swearing, it's just made up, EVERYTHING was just made up.