Although if you follow this step, it could help you figure out if it was a scam or not, what you must know is that, in groups like that, after a victim has been scammed and duped off a huge amount of money, the scammers will remove him or her from the group. I almost fell victim to this kind of stuff some years ago, but it was not a telegram but rather on WhatsApp. There were more than 100 people in that group, and to be sure that it was a trusted platform for investment, I decided to send a DM to the members, requesting to know if they had truly benefited from the system before, and those members said yes and even showed me evidence of payment received.
I felt convinced and was almost on the verge of investing when someone joined the group, I guess through a referral link, and then he began to rain abuse on the moderator of that group, calling him a cheap scammer. Immediately, he was removed from the group, and his comments were deleted. That was how I got saved.
So, what I am trying to say is that, even if there are a lot of members in such a group and they are giving good reviews about the platform, don't be fooled by them, it could still be them and their leagues of friends who have well planned how to scam people.