As long as you work hard at something most likely you're going to get it, if you one believe in yourself(Stop Dreaming and start working)! It's pretty much true just give it all you've got!:)
I find it interesting that your article focuses just on celebrity. There are plenty of successful and ambitious people out there who are not famous actors or singers.
One thing you maybe should have mentioned is charisma. You just have to be likable, really. If they don't like you as a person, chances are you're not going to make it. It really helps to be beautiful inside and out.
Though you have a point, another MAJOR thing to considar is a lot of these people knew someone in the buisness. If you think about it, a lot of child actors have had actors as parents, and Paris Hiltion had money to make herself famous. It all comes down to who you know, and how much money you have. But some as you say, however few, do make it by being in the right place at the right time.