Absolutely, wealth and income are very different. (I went for income, because that's what the OP is posting about, but clearly wealth is also a massive factor.)
Another quick google says that about 5.8% of the UK population own total assets of £1 million or more. So, a much bigger percentage than the six-figure earners, but still definitely a minority. (£1 million is obviously an arbitrary figure - apparently if I make the figure £500K in assets then that's about 23% of the population, which is pretty sizeable. Maybe £500K in assets is enough to make you protective to the extent that you vote against political parties who favour higher taxation/wealth redistribution?).
And yes, the six-figure earners do contribute a lot of income tax, but I don't think that too many of them would up sticks and move countries if the top rate of income tax went up by a few %. So a government could afford to piss them off a bit. I'm not suggesting that this is the best solution, though (a wealth tax on the very wealthy might make more sense, although I guess that population is more likely to just move elsewhere if they don't like the tax system.)
What really puzzles me are the large numbers of lower earners who vote for political parties who are very much against wealth redistribution/higher taxation for high earners. It seems to be at least partly an emotional thing ("benefits scroungers shouldn't be subsidised by working people"). Some media and politicians are totally playing into that emotion, and exploiting its power to influence those voters. Whereas I think that actually better public services and less income inequality would benefit pretty much everyone overall.
Sorry, just rambling and thinking aloud here.