It's not easy.
Let's say that you're becoming successful with that group and you're building up a community. The likely of being bombarded by scammers on your group is possible.
But you can maintain them through you alone or someone that will work to filter your members. If there's none that you can see, I have the same thing to say about in the gambling discussion, there are too many pickers and predictors there that you can find.
As the group is growing, expect that there will be trolls or scammers that will try to explore the channel. It is true, better look for prediction threads in this forum in the gambling discussion boards. There are so many good insights already that you can get from the members here. For me, that's more than enough. But maybe, the OP has other goals for his group.