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 later on.
That's true they will imitate your group they will imitate you and they will use your name to scam people, if you want to form a group, telegram is not the best place to create one you can create channels or you can create an official thread here it's transparent and you'll know right away if a member is trusted or not and you can have a healthy discussion that will add to user's experience.