And I always counter that argument by suggesting that you look at the basic math.
I spend $10 on lottery tickets when I remember, probably every couple of weeks. Let's call it $250 a year. If I didn't spend that, I'd have an extra $250 a year (my winnings just get recycled back into the lottery). What could I do with $250 that would profoundly and fundamentally change my life for the better?
Let's look at it over ten years. $2500 is an OK vacation somewhere sunny. Nice to have, but is one additional vacation every ten years going to profoundly and fundamentally change my life for the better? Is it a vacation I wouldn't otherwise be able to afford? How about over fifty years? $12,500 is an OK used car. In the grand scheme of my life this money has next to zero opportunity cost.
I put it to you that unless you are on the breadline and every dollar and cent counts, you're stupid not to play the lottery. Sure, the chances of winning are infinitesimally small, but giving yourself a small chance to profoundly and fundamentally change your life for the better at the cost of absolutely nothing is a no-brainer decision. You're an idiot if you don't play.