I think people don't (at least in the US, and probably globally, generally) begrudge people what they view as "fair" rewards, especially if they themselves might have a shot at them. Most of the political supporters of low taxes in the US are actually not incredibly high income, but people who think they may have high income in the future.

If you view most wealth and income as coming from fraud/crime or deceit, then it is much more reasonable to want some kind of confiscatory taxes. I think in the past, most Americans with relatively high incomes (doctors, small business owners, etc.) were well respected for contributing more value to the community than they took out in salaries. It is a lot harder even for me as a libertarian to defend those who make huge amounts of money from wall street, government regulation, etc.

In most third world countries with pretty open class warfare, the rich have largely made their money from extractive industry or other exploitation. I'm not sure if this is cause or effect -- there's a strong argument that living in a country where wealth only comes from that kind of thing actually turns your country into a horrible place to live, any where anyone who would otherwise be productive would then want to flee to be productive elsewhere.