Every now and then if I'm feeling frisky, I might buy 1 lottery ticket with 1 pick for the next 20 lottery events, for mega millions, that's 2 months of "dreaming". Other times I won't even think about it. And in the end, the money goes into important things like education. I probably spend ~50$ a year doing that.
You could try to get them to scale it down like that. Still get to "live the dream", without breaking the bank, but in the end the lottery is probably the least of their monetary pitfalls, and you can lead a horse to water...