(how) is this a scam?

My roommate has been talking to a girl in the Philippines that he met on Tinder (he does this sort of thing). She's asked him for money a couple times, and I've had to talk him down from that. Then last night she sent him a screenshot of an Etherium wallet with a $100k balance, saying she didn't know what it was or what to do with it. She says she got it 'from a friend.' My roommate is overjoyed by this stroke of luck and is helping her get a bank account so he can help deposit this money in there. How is he going to get scammed, here? I'll try to keep it from getting too bad if I know what to look out for. He does a fair bit with BTC and feels like he would know if he was getting scammed, but I don't think he's using his brain at the moment.