You would think, but these people do consistently vote against their own best interests. You can lead a horse to water...
What matters is voting consistent with principles even if they aren't in your best interest.
For instance, should you vote to abolish police and courts, so you don't have to pay taxes for them? In the short term, that would net you more money. In the long term, it would mean you'll be living in a lawless wasteland and someone will rob and murder you.