Luck, working smarter, working harder.
Luck is a major factor for everyone, but you can't control it. You can certainly influence working smarter, but it is often a matter of juding in hindsight what was smart rather than determining it before hand. Working harder is much more under our control than the others.
It is important to acknowledge luck. This helps use be humble in our successes, not be too devestated in our failuers, and be compassionate to those less fortunate. It is also just plain true.
It is also important to try to work smart - creating a startup, writing a novel, etc at least has a chance of creating huge rewards and even changing the world...the odds of changing the world from inside the sweatshop you mention are close to nil.
But it is how hard we work that we can mostly control, and there is some truth to Goldwyn's quote...it just isn't all of the truth.