What should Sam do? Will the police help?
Sam immediately should stop investing there. And if Bitcoin uses legal on Sam jurisdiction then you may proceed report to police although I don't believe they would able to do anything since bitcoin is irreversible currency. However he might try his luck. Its seems Sam has been invested on Ponzi Scheme somehow and all ponzi scheme has been turned into scam eventually. To be honest, Sam is too greedy on your story. Why he should involved with it if he doesn't have enough knowledge? The result is scam, that's how greedy people are getting scam. This would be a lesson for other. Just stay away from them who are offering you hight return on investment.
The police can at least help his friend if they somehow get a hint on the location of the scammer. However, it will not be too easy to do.
Transactions that have been done is anonymous and irreversible, it will be a huge challenge for them to find and arrest the one who manages the Ponzi scheme activity
His friend should have realized that it is clearly a scam at the very beginning, there is no such investment like that. He should have avoided it in the first place.