That's the main problem at the moment. The increased value of RP has encouraged a huge increase in bots abusing the RP bonuses. At today's prices, they are stealing $0.50 cents a day per account and it only takes a little over3 months to get to a payout of $50.
We've improved the bot detection a lot but with an incentive that large, it's like play Whac-A-Mole for me.
Would it not be an idea to only give RP to verified or premium users? So anybody owning 2500 FUN tokens (which is affordable for almost all members) could get the full amount of RP per freeroll or from referrals. I doubt that a lot of bot users would buy the tokens, so that can be a way to reduce abuse.