I have known many people who think too highly of themselves, like Imran Khan (who every now and then claims to know more than anyone else about everything under the sun). Such people are known as narcissists. They have a very high opinion of themselves, in fact they believe they are superior to everyone else on earth.

A relative of mine (now deceased) used to call himself "Azimusshan" (the greatest) even before he had become a millionaire. In his later years he had reformed somewhat. Another close relative will never change. He claims to have inside information on every incident that happens in the country. Although not a lawyer (he's not educated), he conveys the impression that the Chief Justice himself consults him whenever a major case is decided. I've often wondered how his poor wife has so far tolerated him without losing her mind.

I used to know a man who used to tell everyone he knew to consult him for impotence. He would say, "If you find yourself unable to get an erection, don't go to a quack, come to me, I have the medicine to cure it". 

Narcissists are mentally unstable. There is of course only one way to deal with them: ask them to shut up. Of course, in case of Imran Khan, no one around him has the guts to do so. In fact, I doubt if anyone has ever told him he's wrong. Otherwise he'd never have been trapped looting the country.