Yes it is fair that someone who has attracted a larger slice of society's wealth to themselves should contribute more to the general kitty. They got most out of society, they have most incentive to retain the environment they did well in. And they can afford to pay a higher rate since they have more disposable income after needs (however defined) have been covered.
And it makes for a fairer society since the lowest paid and the highest paid can work equally hard, and yet the differential between them is enormous. That is what is hard to see as fair in any sense of the word. Higher rates tackle that inequity. #It is a single rate that would be unfair, it would just encourages the, "I'm all right Jack", attitude that society suffers from every now and again.
Everyone wants a better lifestyle. Higher rates of tax doesn't prevent that as an aim since a higher gross income equates to both a higher net income and a higher tax rate. At the highest levels of gross income the income should not be the incentive any more anyway, what is likely to drive you is the ability to achieve non-income related aims.
I think tax on redundancy payments may be considered a special case since it is supposed to be compensation for the loss of your job, and not normal income. So it would be a separate discussion.