This is silly. If you want $100 on the Knicks to win it all and @DraftKings offers $1,200 while someone on an open exchange offers $1,500, you don’t care who the counterparty is. You care that you got $300 more, whether that’s Citadel or Joe Schmo. That’s what @JasonDRobins intentionally leaves out. There are three main reasons his framing is wrong: 1. Just because a market is facilitated by pro MMs doesn’t mean it’s not peer-to-peer. The stock market is peer-to-peer. StubHub is peer-to-peer. Nobody thinks otherwise bc market makers exist. 2. DraftKings is overwhelmingly owned by the same Wall Street firms he’s warning you about. He is the counterparty he’s describing — except his product bans you for winning and doesn’t allow competition. 3. Counterintuitively a sharp counterparty is good for you. Competition among liquidity providers is what tightens the spread and the sharper a LP is, the better odds they can give you. A sportsbook with no competition on the other side of your bet has to ban winners to survive.