What was the point of the US starting the latest Iraq War?

I don't see any gain from it. We've spent so much money, resources, and lives on a war that makes little sense. The war began because Saddam Hussein was accused of harboring weapons of m destruction, weapons that were never found. Then Hussein was later executed for war crimes, crimes that we were seemingly willing to let go until 9/11. After Hussein's execution, chaos has reigned in Iraq. What is the point of the whole thing? What exactly has the US and Bush accomplished by ruining Iraq? Please, I want to hear your thoughts.