Xenia, I think your point about the gulf between perspective and reality is spot on, and that's why debates such as these will never come to a neat consensus. Those who earn less than 150k, while not envious (and I'm off to pedants' corner soon to bang on about envy/jealousy) look at those who do, and say, "well, it is a lot; you do have more luxuries, etc, and so can afford more tax".
Our joint household income, with me working 50%, is about 58k, which is enough for us, (after 8 years each as students, it still feels positively luxurious!) and DH is just about into the higher tax threshold. people on much lower incomes than us will also say that the higher tax threshold is justified for us. FWIW, I agree, I thinik it is, and I hope, like Quattro, that if HE suddenly became very well paid, that I'd still happily take the tax hike at 150k.
Even people who live within their means tend to expand their consumption with increased income, and blur the line between necessities and desires - think this was what Cote and Will were debating earlier. But I do think that people can and should step away from always just considering their own personal circumstances to try to examine the wider picture, and think about what kind of society we live in.
That's why, as Xenia says, debates on here are really interesting, as in RL you tend not to get quite the same cross-section of people as you do on here. I honestly don't think I know anyone in RL who earns over 150K!