This isn't correct. Asian books (not a geographical distinction but a business model) are not exchanges and they effectively pay sharps to bet with them. This

This isn't correct. Asian books (not a geographical distinction but a business model) are not exchanges and they effectively pay sharps to bet with them. This is why betting syndicates exist, they set prices, and the business model of Asian books is to make it back on volume from having the best prices (and before legalisation, these were the biggest books in the world, they did billions every week in handle). But the business model is different: retail-facing bookies have to win their customer base back every week so they need to spend more marketing. Asian books also do promos but they tend to be one-time (which are cheaper to run), they don't have a non-sportsbook business typically, and they don't comply with regulators. Exchanges do not drive away sharps either. Their business model is largely about providing an environment for sharps. The only times were that hasn't been true is when a syndicate has owned an exchange (this happened with Matchbook). The exchange provides an incentive to invest for people to invest in price discovery, which happens. There is no way for the business to run without someone being incentivized to discover prices. People randomly gambling against each other isn't a business model.