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.?
Bitcoin is not gambling. You are not betting on something. When you buy Bitcoin it is not like you are plainly depending on absolute luck for your investment to either rise or turn to zero. Gambling is actually based on pure luck. And the odds will always be against your favor. Bitcoin, on the other hand, is a currency. That itself tells a lot why Bitcoin is not gambling. Moreover, such currency is being bought and sold resulting to a fluctuating value.