The US didn't invade countries and kill millions of people, and the US gained absolutely nothing in terms of natural resources including Oil. Iraqi Oil contracts went to European players like Total. There is no Oil or anything else of material value in Afghanistan.
Lol. It's conspiracy theories that US Imperialism is driven by defence contractors who can 'make a few billion'. They obviously err on one side of the equation, and can have some influence but they are not the drivers of anything. The Defence Establishment is well aware of the cost of war, they're more likely than the White House to be be realistic about engagements.