The Middle East has a long history of violence - especially religious and political violence - that has nothing to do with the United States. It had been going on long before the US and will continue long after we depart. Imagine a Middle East without the United States. Say they withdraw all forces tomorrow. What does the Middle East look like now? A war zone. The region is not one known for peace. The Lebanese civil war propagated by Syria, the Iraqi invasion of Kuwait, the Iraq-Iran War, threats against Israel, religious and ethnic tension are all present in the Middle East. The United States acts in order to keep regional conflict down in multiple ways. Without the US as an ally Israel would be under attack much more frequently than it is.
If the United States did not intervene so heavily the region would crumble under its own conflicts leaving Europe and countries like