A sportsbook is a risk business, not a prediction business. Almost every behaviour that frustrates bettors follows directly from that.
Limits
Books cap what they will accept on a market, and the cap varies by market, by time, and by customer. Low limits early in a market's life are how a book buys information cheaply: it lets sharp money tell it where the price should be, at a size it can afford to be wrong about.
Shading
Prices on popular sides are frequently worse than the book's own estimate, because the book knows which way recreational money leans. Public favourites, popular teams, and overs are the usual candidates.
Account management
Books profile customers. Consistently beating the closing line is one of the clearest signals a book can use, which produces the awkward result that the best measure of skill is also the fastest route to being limited.
- Stake limits reduced without notice.
- Promotions withdrawn for specific accounts.
- Delayed acceptance on individual bets.
Note
This matters for anyone evaluating a betting record. A strategy that works at small stakes may be unavailable at any size that would matter, and a published record rarely mentions whether the prices in it were actually obtainable.