Hey Trafalgar,
Consider this:
If "stupid people" have low ability to pass the marshmallow-test, it means they are unable to save money for the future in a regular way, however, if they play the lottery then they are doing something like an inverse insurance that gives them an occasional financial boost comparable to saving money for the future.
By taking into consideration the context, what looks stupid can be seen to follow a rather intelligent strategy, e.g. given the context that you are unable to think reasonable thoughts yourself, it would be an intelligent move to ask an authority figure.
EMPATHY is the QUEEN of INTELLIGENCE
Lol.
Or - If "stupid people" have low ability to spend their money in a smart way (since they can't accurately estimate which products have the best price/quality ratio), by losing money on lottery they are actually transferring their wealth to smarter people, who will probably spend that wealth in a more optimal way. Thus, they are actually making a personal sacrifice as part of a grand strategy to allow the society to spend its wealth in a more optimal way.
Heh, either way, the "stupid" people are transferring their money to the wealthy. Either the "stupd" people squander the money or give it to the state, which collects billions annually. Money follows knowledge.