Why they exist
Every bookmaker builds its price from its own information and its own customers. When one is slow to adjust after news, or when its clientele piles heavily onto one side, its price drifts away from the rest of the market. That gap, measured against another operator, is the surebet: it is not a mistake about the sport, it is a mistake about the price.
Who closes them, and how fast
Money closes them. Professional bettors and the bookmaker's own automated systems detect the drift and the price moves. In big markets the adjustment is almost instant; in small markets it can last a little longer, but there the stake limits are lower and the margin does not repay the effort.
The real problem: account limits
Bookmakers recognise patterns. Always taking the best price, in odd amounts, right before the adjustment, is a signature. The usual answer is not to ban you: it is to cut your limits until betting stops being worthwhile. Arbitrage does not die from a shortage of surebets, it dies from a shortage of accounts.
The costs that eat the margin
Deposit and withdrawal fees, exchange-rate spreads, your own time, and the risk of being left with only one leg covered. On margins of one or two per cent, any one of those four is enough to turn the operation into a loss.
What surebet software sellers are actually selling
They sell speed and alerts, which is real. What they do not sell is the uncomfortable part: limited accounts, capital spread across many bookmakers, and the manual work it all demands. If the promise is guaranteed passive income, you already know what kind of product that is.
The less glamorous alternative
Looking for value on a single side, with criteria and controlled staking, does not require capital at six bookmakers or racing a clock. It is slower and much harder to sell, and it is what keeps most long-surviving bettors in the game for years.