Well consider the fact that there is currently no conflict and no evidence that one is going to start. The Roman republic went on for 700 years with both a republican democracy and what most historians describe as a highly unequal and oligarchical distribution of power and wealth. Perhaps it fell eventually due to class struggles between the working class and the aristocracy but if it was truly incompatible, then fine it existed in a state of “incompatibility” for literal centuries and there’s no reason to believe the USA and other capitalist countries will be any different. And no reason to believe something better will come along after.
So if democracy and financial oligarchy are incompatible, why does it matter? And btw there’s probably a ton of “incompatible” things that depend on the eye of the beholder. We had racist laws enacted by statute, foreign wars, internment camps, espionage, immoral scientific experiments done by the government all could be described as incompatible with democracy. The reality is that democracy is rule by majority (nothing more, nothing less). Whatever the ethos or the common morality is will be compatible with democracy. Anything done by the elected leaders of the 51% is compatible with democracy.
Don’t get me wrong democracy is better than any other option but we need Democracy+ to really guarantee a just and equal society.