CharliHall: “Chazal didn’t see gambling as a productive enterprise so they pasuled any professional gambler for eidus.”
Which, seemingly would not apply to buying a lottery ticket, since Chazal were referring to someone whose occupation was gambling, not the occasional gambler. As for the reason given by klach of stealing, as yitayningwut and frumladygit pointed out, there would not be an issue with a lottery ticket.
I like Wolf’s approach; once in a while when the pot’s big.