I'd take the groceries. I don't buy lotto already, because it's a waste of money, so why should I give up $50 of something useful for lotto? You might say it's different because it's free anyway, but it's functionally the same as spending on lotto; for example, who's to say it wouldn't be $50 of my own money I'm spending on lotto, while the man's gift just allows me to spend $50 more of my money on something else, given that all money is interchangeable?

Lotto preys on people's hopes for salvation through a large fortune. It's exploitative. And statistically, the more you spend on lotto, the more money you lose.