Don't forget the big drug mafia, they obviously have a lot of wealth but are not tracked, so they won't put their names on the list of the richest people in the world. 
Good call, Escobar was worth around billions already during his height of fame. And it he continues and adjusted to this day, Probably close to a Trillion as well. I guess only legitimate businessman like Bezos and Bill Gates and W. B. net assets can be found because they're high celebrity profiles. But I will assume that somewhere around the globe, there's some family or person whose net worth is more than the 3 combined.