I'm not sure I'd say "brainwashed" -- this is a founding mythos of the United States. It's embedded in our most sacred documents -- the Declaration of Independence, the Preamble to the Constitution, etc. -- that the individual (in theory) reigns supreme and (in theory) has ultimate control over his/her life.
It's a noble ideal, truly, but also a damn convienent excuse for those in power ("I/my ancestors didn't get lucky, they made smart decisions and worked hard, and so did I, so I succeeded") and those in poverty ("I can win if I just work harder/emulate those more successful than I -- ultimately I'm in control and nothing else matters").
It's both our ace-in-the-hole and our fatal flaw IMO.