They don’t pay income tax, but they do pay tax. They pay payroll taxes when paying employees, and those employees have to pay income taxes on those wages.

If you buy american, some of that money will go to the feds in taxes, and the US has a major corporate tax evasion problem. Both are true.

People rarely change their minds about things they believe when directly confronted. Its seen as an attack and makes them defensive and more certain in their ideas.

They have to learn for themselves that they are wrong to change their mind. You can steer them in that direction. Appear genuinely interested and ask leading questions. Subtly guide them into having to confront the contradictions in their own beliefs.