The American Dream not only exists, it's real.
The part that people neglect to mention is that it is hard. It requires both effort and a certain amount of luck. If it happened all the time, to every body, no matter what, it certainly wouldn't be a Dream.
Establishing and accepting that upfront is part of the secret to understanding how to get it.
Most people like to take the easy course, and the easy course is to become what everyone else wants you to be. There is the slightly less annoying alternative of being what everyone else needs you to be, which has its own profitability and emotional satisfaction, and is definitely something worth looking at.
But you can be anything you want to be. You just have to work hard and get lucky. And keep in mind that luck is as much working hard to put yourself in the right place for things to be going your way as anything else.
Your job, should you choose to accept it, is to step up and decide if you're going to make it happen or let it happen. If you're going to make it happen, you pretty much already know what you need to do. If you're going to let it happen, you let a lot of other things happen along the way.
I know which one I prefer.