In that case, how many of those non-karachiites passing judgement on karachi have actually visited karachi for more than a few days? As for those people who did that (how ambiguous), let me tell you that they were hindus and parsis that since partition moved to india (a lot). Sindhi muslims were treated like scum back then by their balochi sindhi overlords and are now as well even with the supposed rise of a sindhi middle class, though there is none in the feudal rural areas.
He was born in karachi. A lot of people have their early education in Pakistan and then go to the US or UK like Jinnah did to become a barrister.