Of course, no one plays the lottery for the expected value of a ticket. Doing so wouldn't make much sense seeing as the $2 cost of a Powerball ticket is almost always more than the expected value (the house essentially always wins). But if that's the case, why were 440 million tickets purchased for Saturday's drawing?
Economists, and our revealed preference, point to the idea that there must be a certain level of utility derived from the thrill of the game and the chance at walking away with a large jackpot. Behavioral economists, citing the foundational work from psychologists Daniel Kahneman and Amos Tversky, would also add that humans have a tendency to overestimate low-probability events, such as winning the lottery, making any perceived expected value of a lottery ticket much higher.
The point is there are many logical reasons to explain what is otherwise considered to be an irrational gamble. However, if you're looking to rationally maximize the worth of your irrational $2 gamble, choosing to play when a record-jackpot is stimulating a news frenzy and mass hysteria might not be the best strategy.
But then again, you can't win if you don't play.