It doesn't seem like it's strictly true that they don't charge trading fees.
From their docs, it looks like they charge fees to bet "takers" (as opposed to makers), but exclude the geopolitical and world-events markets where they don't charge fees.
I have to imagine that may be related to some of the blow-back towards prediction markets about profiting on topics like war & their potential for manipulation.
Given it sounds like the bot bets everywhere other than sports, many of those categories would likely have fees in this case.
Polymarket charges “taker” fees (people removing liquidity by matching listed orders) on most markets. Geopolitics markets are exempt. A portion of the collected fees then get redistributed to “makers” (people who provide liquidity by listing orders for others to match). Presumably the rest of these fees make up polymarket’s revenue.
Which is essentially also providing a platform for making the book for the other platform, on which 'bookie fees' are charged, but Polymarket itself only keeps a certain cut of it, for facilitating but not actually book-making.
