Every tax ever implemented by government has been initially sold as a tax on the rich. The people voting for it assume they will never be taxed because they aren't currently rich. But, there is never enough of other peoples money to spend. So, taxes expand and/or increase to include more people.

The original income tax was sold as 1% on mid income and 2% on high income. At the time more than half the country was not going to pay any tax.

Which is why the current administration and their (very rich) backers prefer tariffs to income taxes...