It is rare that terrorists manage to actually kill or injure a lot of people, but that is not what they are all about. They are called terrorists because they instill terror. If any of us avoid a public event or location because of the threat of terrorism it means they have accomplished their intent. If we lose one nights sleep then the threat is real.
Of course terrorism is a threat... Just as tripping and injuring yourself is a threat; But is it a significant threat? No. There are a huge variety of facts for this: Did you know that you are more likely to die from hot weather/drown/killed by a police officer than be killed by terrorism. Due to huge media publicity and propaganda, the general public has been fooled into thinking that they are at risk and that going out and invading that countries that contain these (very few) terrorists is warranted e.G. Iraq, Afghanistan etc.
The us is the greatest threat to themselves. We have the idea that whatever is going on in the world is our problem and we must intervene
. Are actions on foreign policy are the most important decisions we make. So terrorists arent the real threat its the mistakes we make