Tax revenue as a percent of GDP is historically been in the 19-21% range regardless of how high the marginal federal tax rates have been. This has been the case from 1950 to the present (see Hauser’s Law). Of course the enlightened ones in Washington spend 25% of GDP, hence the deficit.
As for your quoted rate of 27% of GDP and how is anyone paying over half in income taxes, did you just ignore the 47-50% who pay NO income taxes at all? Further, the point made about taxes was not just federal income taxes but all taxes. Just add up all the far ranging taxes paid. Some examples include SS, Medicare, property, state/local, gas, and sales taxes. At least everyone has to pay some of these as well but high income productive types certainly pay more in dollar amounts and yes it does approach 50%+.
So, if you accept that tax revenue is going to be around 20% of GDP the way to increase revenue is to increase GDP with economic growth.
The 27% number I found was inclusive of all levels of taxation.
No one has to struggle to pay less than 50% of their income in taxes. It’s just a demagogic talking point with no basis in reality.