That's why you have to research first before doing something usually if it matters of sending money to someone online. Because there is bigger risk with this kind of scheme, like doubling bitcoin, for several hours/days.
Annd thank you for sharing this thing here, so more people will be aware Of this site
That's the exact reason for this post. 100$ is not big amount for me but this post may save hundreds of $ from the potential victims of this scammers.