That argument is certainly true, but it applies to nearly everyone. Almost no one is politically well-informed enough to be sure of what’s in their long-term interest, with most people not understanding for example economics or environmental issues enough to take an informed position. So politicians frequently resort to short-term fixes, such as tax cuts, to keep people happy and voting for them. If more of those short-term fixes benefit minorities, that still isn’t worse than if they benefit majorities.