I'm a Brit. You're talking to me like I'm an American. I understand your sentiment, but I disagree, "you get on with changing the world", which should include

I'm a Brit. You're talking to me like I'm an American. I understand your sentiment, but I disagree, "you get on with changing the world", which should include preserving that which already exists. People forget about the concurrent attack on the Pentagon on 9/11. If all that can happen in the space of less than an hour, that was not a threat to be ignored, and more would have followed had something not been done. You're also conflating improving national security with boots-on-the-ground searching for supposed WMDs in another country. The two things are not the same in any way. Your argument is total "whataboutery". If you have holes in national security that allowed something like 9/11 to happen, including the attack on the Pentagon on that same morning, you do something to prevent the likes of it, or worse, from happening again. You can't even argue against that.