Or maybe... She got lucky with some investments, maybe real estate. That reminds me all the stories of engineers who retire early by "saving instead of spending" that start by "I got 500k from stocks when the startup I worked for got bought out".
Sure, saving every year and investing instead of buying everything credit is a good thing, just like avoid to sink all your savings + 25 years mortgage when you buy a house, and many Americans especially need to be reminded that. But showing a lady who end up with 6M "just by playing the long game" sounds a lot like the old Adam Smith/American dream bullshit. "If you work hard and save, one day you'll be a millionaire". That's bullshit. You can't become a millionaire just by saving your blue collar salary (or school teacher salary) and saving up instead of overspending.