Hard work, luck, and being a bit smart. If you are a smart person who knows what he should do, work super hard and also after you worked hard, you get a bit of luck that goes your way too? Then you are going to be rich.

I have seen insanely smart people, who are lazy and fail, I have seen people who work hard but not smart enough to run a business, I have seen people who are super smart and worked hard, but then fires broke out in California (where he was) and all of his business was gone (thankfully insurance covered most) so there can't be really any of these missing. You need brains, grind, luck and without even one of them you are going to end up with plenty of trouble. So we need to make sure we do our part, which is hard work and brains, then luck is out of our reach.