I have met a lot of people who made a million or so selling their tech stock options after they left/sold companies . Then they invested that money and now are very wealthy.
My dad is well off because he is a frugal SOB who sold his calif house that he had owned for around 15 years and made a lot of money, then invested and rented out rooms to his deadbeat son, and is now sitting very pretty with a nice estate to leave to his other (non-deadbeat) kids (YAY!)
I also know this guy who inherited a lot of money then his wife insisted that they continue to live below their means, let the invested money grow. He ended up very wealthy, wealthy enough so that when they divorced he was able to financially set up his ex-wife very nicely, attract a very attractive replacement wife and buy her a McMansion. His ex-wife continued to live below her means, saving and investing, learning a lot about personal finance. She is now more financially secure than she was at the time of the divorce.
I think the key ingredient, at least in my examples, is that no matter how you acquire money, earning or inheriting or whatever, the key to keeping it is to make smart decisions and not go hog wild keeping up with the proverbial Jones who have not been saving at all, instead buying houses they can't afford, going on way too expensive vacations and buying anything and everything they want.