In traditional slots you pay a coin, and if a certain sequence comes up, you get some winnings. I think everyone will agree that's a form of gambling.
In bitcoin, to create coins, you pay some electricity, and if a sequence of 0's comes up, you win some bitcoins.
Is this aspect a form of gambling?
And if so, is that illegal in the U.S.?
I think yes. When you gamble there is a chance for you to win or lose and so when you invest on bitcoin. The presence of risk is there to both of them. Strategies is needed when doing both and so with luck.