Gamble

The American Heritage Dictionary lists the following four options for the definition of the word gamble:

1. To bet on an uncertain outcome, as of a contest.
2. To play a game of chance for stakes.
3. To take a risk in the hope of gaining an advantage or a benefit.
4. To engage in reckless or hazardous behavior: You are gambling with your health by continuing to smoke.

Can gambling only be done in a casino, online or otherwise? Why is it that no one considers entrepreneurs gamblers? I think there is a big gray area + gamblers could be perceived as willing losers who occasionally win.

I think the concept could be applicable to gem business. I know many who are engaged in the pursuit of speculative profits who, by their own lack of skill are really gambling + they are knowingly trading gemstones without an identifiable edge.