What's the difference between a prediction market and a sportsbook?

A sportsbook is a bookmaker — you bet against the house and prices include a margin (the vig). A prediction market is peer-to-peer — you buy and sell YES/NO shares against other traders, and prices always sum to $1. You can also sell your position before the event settles.

Is Polymarket better than DraftKings for betting on sports?

For sharps, usually yes: lower effective fees, no line-shopping needed, and you can exit positions early. For casuals who want teasers, parlays and same-game combos, DraftKings has a wider product menu. Polymarket is a trading venue; DraftKings is a sportsbook.

Are prediction markets legal for US sports betting?

Kalshi has CFTC-regulated event contracts and offers some sports markets to US residents. Polymarket does not currently serve the US. Traditional sportsbooks are legal state-by-state.

Can I be profitable long-term on a prediction market?

The math is friendlier than a sportsbook because there's no house margin — the spread is set by other traders. That doesn't make it easy: your competition is other sharp traders instead of a passive bookmaker.

Prediction Markets vs Sports Betting: Polymarket vs DraftKings

At a glance

The core difference in one table

	Sportsbook (DraftKings)	Prediction Market (Polymarket)
Counterparty	The book	Other traders
Effective fee	4.5% vig (avg)	0% + spread
Exit early	Cash-out at book's price	Sell at market
Limits winners	Yes (accounts capped)	No
Product	Spreads, parlays, teasers	Binary YES/NO only

Fees

Why the vig quietly kills sportsbook bettors

A -110/-110 sportsbook line is a 4.55% margin. To break even long-term you need to win 52.4% of the time. On Polymarket the spread on a liquid market is often 1–2¢ on a 50¢ contract — a fraction of the sportsbook edge.

Over 1,000 bets at $100 stake, a 4% vig costs you $4,000. On Polymarket at the same volume, spread + gas cost you a couple hundred dollars.

Edge

You trade against different people

A sportsbook is a passive counterparty. It doesn't try to out-handicap you — it takes both sides of the book, balances the action, and pockets the vig. You beat it by out-thinking a static line.

A prediction market is other traders. If you're not sharper than the median participant, the market will eat you. The upside: no one can ban you for winning.

Legality

What's actually legal where

DraftKings / FanDuel: legal in most US states with individual licensing. Not available worldwide.
Kalshi: CFTC-regulated federally in the US. Includes some sports event contracts.
Polymarket: available in 100+ countries; not currently open to US residents.

See the deep dive in Polymarket vs Kalshi for the fee and product differences between the two prediction markets.

FAQ

Frequently asked questions

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