Most rich people evade taxes
legally, by following the letter of the law but structuring their assets and income in a way that they just happen to owe no taxes.
The IRS are consummate bureaucrats. They don't write the tax code, they just enforce it. They enforce it quite firmly, but if you happen to get a loophole written into the tax code and drive a billion-dollar LLC through it, they aren't going to care.
McAfee made the mistake of open defiance of the tax code, and that's a big no-no. If the government starts letting open defiance slide, everyone will openly defy it, and there won't be a government. That's why they threw the book at him.