Why do people use profanity?

In my opinion the use of profanity indicates a lack of intelligence or education. Certain profane words seem to be used in the place of adjectives and adverbs as well as the nouns and verbs of a sentence. Among groups of people who use profanity against each other, each is trying to impress their friends by all the profanity they know as if it is something to be proud of. The more a person is in the vicinity of people who use profanity, the more likely they are to start using it themselves. Others may have been raised in homes where profanity is the norm and don't know any other way of expressing themselves. Once in the habit of using profanity, the person isn't even aware of how much they use it.