Extremely rich and extremely poor people tend to be Democrats, whereas people in between tend to be Republicans.
I'd like to see some statistics proving that please, especially for your assertion that extremely rich people support the Democrats. It seems to generally be the case that among wealthier people the upper-middle class (and 'soccer mums' etc.) support the democrats rather than the richest in society.
Is Bill Gates a Democrat? I thought I heard before that he was. Warren Buffet is, so that would make the two wealthiest people in America Democrats, at least. So that proves that Phillip is right once you get up to the $30 billion net worth threshold.
In all seriousness, I don't think there are any exit polls that break it down enough to prove whether he is right or wrong. All we know is that those with an income above $100k/year are the most Republican group in exit polls that ask about income; those above $100k/year aren't broken down any further.
The "cutoff" income at which those above that level lean Republican and those below lean Democratic is about $40-45k/year. This is slightly below the median income of all voters (which is about $55k/year), which should favor Republicans, except that the poorest voters (under $15k/year) favor Democrats more strongly than the wealthiest (over $100k/year) favor Republicans.