What if we phrase a Pascal's Wager-like problem like this:

If every winner of a certain lottery receives $300 million, a ticket costs $1, the chances of winning are 1 in 250 million, and you can only buy one ticket, would you buy that ticket?

There's a positive expected value in dollars, but 1 in 250 million is basically not gonna happen (to you, at least).

vroman: Two words - rollover jackpots.