A couple of the early people really having their money doubled would probably do wonders for spreading the scam as fast as possible.
Not sure if they did or not. But when this scam was around on Runescape that was generally the way it worked.
You don't need to send it any actual users. Just set up some transactions between wallets you control and use some sockpuppet accounts to make apparent 'winners'.
Wait til the next runescape scam - buying $TSLA 2400 - just send it to my account here first and I will send you the money in BTC.