There are a lot of players around the world. Not every games are favorite in all region. Some likes soccer, some maybe esports or some cricket or others.
Basketball and boxing are two of the sports that are very popular here in our country, I bet on these two, but not on casinos I refer to betting against a friend because it's easy to collect as we both watching the game, it's more enjoyable if you have a friend sitting beside you watching your favorite sports
Which one are you mostly placing your bets on? Besides, do you think gambler don't care which sport it is. I have seen gambler who don't have any fucking idea about cricket but he used to bet on cricket.
I don't see any issue at all if they got a tip that a certain team will win against the opposing team he can bet on the team even if he doesn't know anything about the sports, gamblers will bet if they see good odds regardless if they know the sports or not.