I'll refrain from being a dick and talking about "not voting their interests". They have their opinions and should stick to them.
I prefer an honest labourite like TNF (not sure how rich he is) to the kind of snobbish latte liberalism that can be found in the upper middle class. Talking about union power just bugs me less than the endless talk about gun control or foreign aid.
Ah, of course the kind of latte liberals who don't particularly care about the actual income levels of the poor of their own country actually are voting their interests, or at least not in a way to actively endanger them (they are not voting to maximize their future earnings... they're not THAT greedy.)
And the degree of influence they've had over the post-1968 left and especially today IS a problem.