Yup. I've already read a few articles on this. No matter how large the pot, when you factor in taxes and the possibility of multiple winners the expected value of a lottery ticket is always less than 1. So yes, it's just giving away money.
Interestingly enough, there are exceptions to this. Certain games can be won in the long term, statistically. Some require knowledge of statistics due to faulty generating algorithms (eg, look at one of those scratchcards that list a bunch of numbers you're supposed to match, they might give hints as to what's under the scratch part); and some just with enough money (eg, if you buy 60% of the tickets, chances are you'll win over 60% of the pot considering various prize tiers.) The latter require very large purchases.
With that said, most of the exploitable ones get fixed relatively quickly (and also tend to require a degree in statistics to exploit); and most of the ones requiring bulk also get fixed to pay a little less. But it's been definitely known to happen with various state- and nation-run lotteries and games in the US and Canada.
Interestingly, I'm not aware of any casinos that have similar flaws in any of their games, unless you can count cards in blackjack. I dunno, maybe some have loss-leader penny slots where you can expect to win 50 cents a day on average, just to put more butts in chairs who then go buy a $10 meal or make the place look busier or whatever.
Now that we're done talking about that cool fact, yeah, you're on average not gonna win money in any lottery. Still, though, many people buy "the dream" of what they'll do with that $150 million post-tax chunk of change.
PS: If you're going to play a lottery where you pick numbers, try making many/most/all of your numbers above 30 or so. The winning numbers generated are fairly evenly distributed, but the numbers picked by people buying tickets tend to include things like birth dates (day of the month) and so on, so they're not evenly distributed. So if you ever happen to win, you're less likely to have to share your prize if you pick the less-often-picked numbers.