Why are fools denounced as dementia and idiots?

Because simple-minded people are reckless and not so careful, they are prone to make mistakes and make jokes, which will give people the impression that they are stupid and not smart enough. Some people who don't like or can't accept this kind of behavior or speech will regard it as something abnormal, but a problem of mental retardation or slow behavior. Therefore, idiots and dementia are generally used to describe such people.