In a friendly Poker game, everyone comes in with some amount of money, and by the end of the night the money changes hands. Some are winners, some are losers. T

In a friendly Poker game, everyone comes in with some amount of money, and by the end of the night the money changes hands. Some are winners, some are losers. That's a zero-sum game. When you go to a casino to play Poker, as condition to play you must pay chips every hand called a "rake". When you and everyone else walks out of the casino while there may still be winners there will likely be more losers, and the total is negative. The casino has some of your money. That's a negative sum game. With mining bitcoin is equivalent to the casino scenario. Except instead of the casino keeping the money as profit, it's using that money to buy energy. Then you add onto that the exchanges taking a fee on top of that.