Cosma Shalizi defends the lottery:
The benefit to playing the lottery comes entirely between buying the ticket, and when the winner is revealed. During this interval, someone who has bought the ticket can entertain the idea that they might win, and pleasantly imagine how much better their life could be with the money, what they would do with it, etc. It's true that in some sense you always could just make yourself think about "what if I had $280 million?", but many people find it very hard to get their imaginations going on sheer will-power. A plausible and concrete path to the riches, no matter how low the probability, serves as a hook on which to suspend disbelief. In this regard, indeed, lottery tickets are arguably quite cost-effective. If a $1 lottery ticket licenses even one hour of imagining a different life, I don't see how people who spend $12 for two or three hours of such imagining at a movie theater, or $25 for ten hours at a bookstore, are in any position to talk.