I would just ask my friend if they know it's a scam.
If he says, "Yes," then that let's me know that he knows what he's getting into and leave it at that.
If he says, "No," then I would explain what I know about them and let him still make the decision for himself if he wants to continue with it or not.
Not all cloudmining services are a scam, I would not say that Genesis-mining is a scam.
Now, if it will make a profit, that's another question.
I've personally made a profit through Genesis-mining by getting paid in Dash and selling it when the price was pretty high a couple of months ago.