There are friends in the group complaining that PM takes more cut than a casino.

I initially wanted to argue, but after checking the official Polymarket docs, I found that this claim is supported by the data.
Crypto 5-minute market, price around 0.5, taker fee is 3.5% of each transaction amount. 20% of that is returned to the maker, leaving the platform with a net 2.8%.
Other categories are lower: sports 1.5%, politics / tech 2%, weather / economics 2.5%. Geopolitics has 0 fee.
Baccarat banker bet house edge ≈ 1.06%.
Just considering the fee, PM Crypto’s one-sided platform cut is 2.6 times that of baccarat. In the worst case, round-trip trading (buy + sell) results in the platform taking about 5.6%.
But it’s not exactly the same structure as a casino.
Casino: the house always wins, and the expected loss for players is -1.06%.
PM: the protocol takes about 2.8% per trade, and the remaining money is redistributed between maker and taker in a zero-sum manner.
In other words, the protocol itself acts as a "thin house," even more ruthless than a casino. But the bigger losses for retail traders don’t actually come from this 2.8%, but from the order book — many of the maker orders you eat are not cheap; they are often willing to let you take.
Plus slippage, it’s normal for retail traders to lose money even when betting on the right side.
Ways to save a bit:
· Use limit orders as a maker, avoid fees and get rebates
· Geopolitics market fee = 0
· Choosing YES / NO side doesn’t save on fees: the $0.30 and $0.70 dollar fees are symmetrical
· Crypto-related categories have high fees; if possible, choose lower fee / zero fee categories instead of the most expensive tier
Another common gray-area tactic — "using a small account to eat your own referral." Each taker fee of 30% flows back to the referrer, so the 3.5% can actually be pushed down to around 2.45%. But Polymarket explicitly states in the Referral Program docs that self-referral can be disqualified at discretion. If flagged as inauthentic trading, the referral account will be frozen, and previously accumulated rebates may be lost.
Small volume isn’t worth the risk; large volume also requires careful consideration.
"PM is more ruthless than a casino" holds true in terms of crypto fees, but you have more variables to choose from — category, price level, whether to be a maker or taker.
In a casino, you can only bet on big or small.
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In the group, we often discuss practical comparisons:
If you want to analyze the data yourself: