8
The near miss by one number
Five of six is the cruellest result in any game, and it is far more common than people think.
Matching five main numbers and missing the bonus turns a life-changing sum into a merely large one, and players describe it as worse than winning nothing at all.
It is also entirely predictable. The whole design of a modern lottery is a prize ladder where the tiers just below the jackpot are far more reachable, that is what keeps people playing, and it is not a trick, it is printed in the odds.
The psychology is called counterfactual thinking: an outcome hurts in proportion to how easily you can imagine the better version. One number away is maximally easy to imagine. Two hundred numbers away is not, and feels fine.
It is also why so many people describe a small win as worse than nothing. Matching three numbers for a few pounds confirms that the line was live, which the brain files as almost rather than as won, and almost is the feeling that sells the next ticket.