And if you own a failed emerald mine you might be poor. If you own an emerald mine that just barely broke even (admittedly that is a bit unlikely), you might end up middle class in the end. Of course you can also end up being obscenely wealthy from such a venture.

I don't think anyone is suggesting elon musk rose from being a homeless person to a billionaire. I guess this internet dispute is whether he made his own money, or inherieted it (e.g. like trump). Whether or not his parents owned an emerald mine doesn't really shed much light on that debate. Its entirely possible they were moderately wealthy but the emerald mine wasn't super lucrative and musk still made money mostly by means of his own combination of skill and luck.