We need to distinguish the behavior of ordinary users from scammers.
Scammers would likely attack this feature by setting up lots of fake accounts with fake credit cards and tipping each other’s posts, hoping to generate a payout before the charge backs start to come back on their credit cards. I already explicitly foil that scheme by delaying the payout period to six months, which greatly exceeds the 90 days that the cardholder has to file a claim. You could develop other anti-scam strategies.
That leaves ordinary users, and my comment applied to ordinary users. Ordinary users won’t reward large numbers of low quality posts.