Religious extremism isn’t coming mainly from the wealthy. It’s dominantly a lower-strata southern thing, with notable metastases all around the country, yet it plays strongly in the US system.
That some wealthy co-opt the extremists doesn’t change the above.
Look at the main Christian denominations associated with extremism, then look at where their main strength is. You’ll find a correlation to the US south.
As an example, look at the Global Methodist Church, which is liberating bigoted congregations from the United Methodist church. So far, it’s main (but not exclusive!) strength is in the south.
When you have concentration of power due to concentration of wealth, the society will become unstable and undemocratic.
So even though wealth isn’t zero sum, wealth inequality is a problem that needs to be addressed for long term stability.