Accumulators are popular because small stakes can return big money. The problem is maths: every leg multiplies the bookmaker's margin, so long accas are usually negative EV even when each pick is decent.
If each leg has a 5% bookmaker margin, a 10-leg acca compounds it into a huge edge for the book. Your probability of winning also collapses: ten 70% picks land together only about 2.8% of the time.
Accas are a good use of free bets because the stake is not your money. Do not use them as an excuse to bet recreationally with real cash.
Treat an acca as entertainment with a small stake, or as a value play only when every leg is genuinely +EV. Never chase a big acca to recover losses.
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