I think you can classify lottery tickets as investment, wheras insurance is, well, insurance. I don't play the lottery because it's extremely unlikely to make me positive returns. I pay for health insurance because I want to cover the unlikely possibility that I have a serious health problem.

There's also the amortization to consider. Over a lifetime I may lose 50% of what I put in to insurance -- but I don't have 50% of what I'd put into it over my lifetime available to me now if I have a large medical bill to pay.