So who, exactly, would have dealt with Afghanistan? Imagine a world where the US renounced all military endeavors and cut all military spending. Do you think that all the problems in the world, ranging from Afghanistan to NK to Israel/Palestine to Sudan to Iran to FARC to Somalia to Pakistan to Rwanda, would just disappear? The rest of the world would have to step up its game and intervent to resolve those problems.
The U.S. divided priorities between Afghanistan and Iraq. Once your government did that, it had no right to complain about operations in Afghanistan going downhill. Most of those problems that you mention would have been resolved post-cold war if the U.S. had stopped continuing its funding and training of dictators and sectarian actors in the region. The Taliban is your creation. NATO and the other nations involved are helping you as a courtesy. (By "you" I mean your country, obviously not you personally.) That good will has been abused by expecting allies to partake in more conflicts as a product of imperialistic attitudes. You settle your own scores and then get back to us about priorities.
The fact remains that many of the direct wars and a large number of the proxy wars being fought by the U.S. could have been prevented in the first place by exercising restraint instead of engaging in hasty interventionist policy. As a result military spending is substantial in order to maintain global base operations. Some of those are because of treaties and that's fine, but a lot are for strategic maintenance in anticipation of future conflicts.
The military-industrial complex in the U.S. arose from the Cold War and needs continual war in order to produce GDP, otherwise it's a lost sector of the economy.
Furthermore, such a power vacuum would create an opportunity for other nations to fill, and I think I know which countries would be most likely to take advantage of such a situation - China and Russia.
China is powerful because the U.S. has borrowed itself into servitude.
The U.S. created the very environment you speak of, where other nations rely on it to fill the power vacuum. The world is grateful for its efforts during the Cold War but post facto it created the international infrastructure for co-dependence. If your nation is to survive the long term it has to be broken. The world will simply adapt. Europe has enjoyed a relatively laid back environment, reaping the benefits of U.S. interventionism for years. It would just have to militarize again and defend its own ass.
You act as though the U.S. is doing everyone a favor but it's just as much about maintaining influence over a broad range as it is about maintaining a good image.
The fact is that a world without the US military is not a world in which you or other Western powers would enjoy living.
Don't presume that the benefits aren't mutual. The opportunity cost that the U.S. suffers from large military spending is one made up for by developments made and shared by its allies.
Everything does everything out of self-interest - that doesn't mean it doesn't help others. Warren Buffet pays his taxes because he doesn't want to go to jail - does his self-interest mean that the thousands of people getting government money because of him don't really benefit from it?
I don't see how you can favor military spending yet attack welfare. Tax dollars fund both of those things and people don't support either. If you reduce one you should reduce both. I'm not suggesting cutting the military budget in a huge way but it's definitely a major drain on the system. Moderation is key, same with welfare and the other social programs. You can't have your cake and eat it too if you're trillions in debt.
The only benefit to war is acquiring more capital which can be used to back U.S. currency, but your country isn't even succeeding at doing that. Assets acquired become high risk due to continual insurgency. The only benefit to acquiring Iraq is using it as a gateway to enter Iran (and thus extend the vicious cycle of the regional conflict), and to use the oil infrastructure to challenge world prices. That benefit is temporary.
We don't provide troops because other countries are more eager to provide them. Countries get paid a set wage for providing peacekeepers, which creates a strong incentive for poorer countries to supply as many as they can. Furthermore, the UN likes to use troops from smaller countries so as to avoid the image of its peacekeepers as occupiers or colonizers.
True.