I agree with your initial statement. Taxes are not linear.
However the following two statements are so incomplete, as to be wrong:
"So if you make a million pus one, your tax is 90 cents or pence. NOT 900,000 dollars or pounds.
Also if you are a hedge fund manager who makes 1 billion a year, you "only" get to keep 100 million. That makes me so sad. The entire world weeps for you."
Even though you do not pay 90% taxes on your complete income, you do pay taxes, not just 90 cts...