Gambling is a fun activity done consciously by the gambler, no one forces you to do it, it's a personal decision made by those who engage in it. Gambling is only a scam when you get defrauded by a casino or sportsbook. A friend of mine told me about how his account got swiped by a scam casino. According to his story he said that he put in his card details to deposit money, after doing that he started noticing that he was being debited by an anonymous source constantly, he had to transfer the money he had left to another account, in this case you can call it a scam. No one is promising you a win, it's 50/50 and everyone is aware of this risk before placing a bet.
It is true that gambling itself is not a scam if it is conducted in a fair manner. However, in your example with your friend, we are talking about a clear scam on the part of the casino, which may be due to the insecurity and unreliability of some platforms.