Hi Steemian
It is difficult to determine whether it is a scam or not, the best way to do this is to do the abput research. According to my research, I think it is not a scam, it is because there are many participants who participate in it. The $ 10 coin worth is not a bad deal and it is still your choice if you want to participate, but for me I appreciate the legit.
I have earned 500 coins for registering in ref: https://sphere.social/?ref_code=ha91gpgfhq1a
but I doubt if this is true on pay or indeed fraud, what do you think ?
Note : if register via Ref: https://sphere.social/?ref_code=ha91gpgfhq1a.
you can just get a free coin.