"Every time one of your sponsorees buys credits, you’ll receive 10% of the amount purchased (5 credits for a purchase of 50 credits, 100 credits for a purchase of 1000 credits, etc.)"
If "player A" gets their friend, "player b" to come in and buy 420 credits for $19.90, player A will already get 42 credits, enough for a Mega Newbloods pack. The rare card player A gets from that pack alone is worth more then 10,000. Plus every single future credits purchase player B makes, gives 10% to player A.
Sounds like a way to weasel that 10% for yourself.