In most cases they are scams, but in the few channels that you can find that show signs of not being scams, they make money at the expense of people's naivety, for example, they send signals of games in which the favorite has very low odds, something like @1.40 because they know that there is a high chance of success. But in the long term, people who pay monthly subscriptions do not make a profit with these low odds even though they have a high success rate, while the channel owner makes a large profit with the monthly subscription payments that people make.