True in many cases, but there were wars before there was capitalism.
No, feudalism has different economic relations than capitalism. It is about farm product graft from land-bound peasants on penalty of death or injury. Capitalism is about wage working. Capitalism emerged in the context of feudalism, so there were periods where both existed side by side, but capitalism is clearly different.
The problem is and always was the power structure and the greed of those at the top of it. It had many different names and forms during history.
That’s describing capitalism, where profit maximization is systemically required for one to fulfill their role at “the top” and monopoly is the best way to increase profits.
Historically, “greed” was not the main characteristic of the ruling class. They did not exist under capitalism. Money itself often meant little. Land, a military, prestige, yes. But money fir money’s sake was officially frowned upon and generally left to the clergy to handle the hypocrisy.
Not all economic structures reward the same pursuits. Capitalism, as an example, naturally selects for those who can accumulate the most and discards the rest, and this process has been the source of countless wars.