They really don't all think alike. Jesse Jackson just wants you to believe they do.
A large percentage of blacks do. Given the history of black people in America, it's only natural, and frankly practical, for black people to be a little paranoid. A little paranoia can keep you alive if you are a target of persecution.
The problem is that the battle for civil rights is, for all practical purposes, over, and the good guys won. That victory presents an dilemna for the democrats, and asundry civil rights industry leaders. In order to garner the black vote block, they have to continually stir up the fears of black people, continuing to fight a war that no longer rages.
The professional rabble rousers are, of course, threatened by black people who insist on thinking for themselves, rather than huddling together for protection against the man. That's why they attack them so viciously.