If I knew I'd die in <10 years then I'd vote for the "short term" solution and believe or not - this would NOT be irrational on my end.
People might have different interests and they vote for themselves.
People might have different interests and they vote for themselves.
Would that be irrational then? Or just selfish? Or both, or neither?
Most rational people where I live also consider the wellbeing of others and will make decisions (and even vote) to make sure others live well besides them.
Is you defition of rationality basically "maximum selfishness and extraction of benefits from others"?