[Izverg04]

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One thing to remember when discussing whether or not playing a game with a large progressive jackpot is +EV is that at some point in time money will have a diminishing marginal utility for you.

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It's pretty clear from this thread that buying a lottery ticket for most is an entertainment expense, not a rational gambling decision. However, a few sound pretty serious when discussing "EV" of this lottery, which is a completely meaningless number. If you estimate a fair price of a lottery ticket, meaning a price for which it would become a good gamble for you and me to buy one (or a few thousand), you'd have to do it without considering the jackpot or any payoff > $100,000, and the price would probably come out to no more than 10 cents, since so much of the expectation is tied up in the jackpot.

Utility(jackpot)*Probability(jackpot)=0.

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$240 million is probably not 240 times more valuable to you than $1 million would be.

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Utility functions have to have an upper bound, otherwise you run into St.Petersburg paradox. If you construct a utility function that doesn't have any of these problems, and can be usable for everyday gambling decisions, you get with a good precision U(+inf)=U(+$100mil)~U(+$1mil), unless winning $1m is not a very significant increase to your bankroll.