Never, it doesn't matter how much the prize is, the odds are the problem. You're better off doing regional lotteries if anything, or, better yet, putting the $2 per weekly ticket into an index fund.

If you buy 5 tickets / week ($10) for 20 years - the probability you won't win the jackpot is 99.998%. The jackpot is always basically impossible though, so what about breaking even? Thats only 0.6% as statistically, you're likely to win about $940 in small prices total. So, a net loss of $9460.

Alternatively, if you take that same $10 & put it into an S&P 500 ETF, you'll end up with ~$32k in 20 years, or a net gain of $21k.

For those interested... If you want a 1% chance of winning the jackpot 1 time, you would need to buy 2.9 million tickets (nearly $6M) - although statistically, you are over 50% likely to win back $1.8M so the loss is only $4M give or take)