It seems like an obvious scam to me.
How do you know they will gamble with your money? They could just keep the 90% and say you lost.
Anyway, why can't you gamble it yourself? Do they claim to have a system? If they claim to have a system, then it's probably a scam.
But you can earn some money on it. If you don't treat it like a long-time investment!
I would not do it ever. Man, stay away from your friend with such a scam proposition. You will earn pretty good money trading honestly. Monitor the market of crypto. Save fiat money to buy alts and BTC when the coins value is low, and sell it when the coins are high. Invest into good ICO, but do not gamble.