Well, he stated pretty clear that ho won't use an escrow, so 99% that it's a scam, 1% that it's not. So here's a math. I might want to risk 1/100 of my wealth. I've got a couple of btc, so I'll probably invest 0.02 btc for this 1%. I guess that's how it works. You lose 99 times of 100 but that 100th makes you rich.