The terrorists who drove those planes into the towers were from an engineering background and knew that the fuel from the planes would do the job of bringing down those towers once they had impacted.
All you have to do is turn on CNN or any cable network and see how they cleanly take down any Las Vegas hotel to replace it with a bigger and better one. They set the explosives and it drops to the ground without impacting the neighboring hotels and casinos.
I agree with Sistersister. We have been blessed to see some wonderful things in our lives. Get outside, get some sunlight, take a walk, meet up with a friend, do some work in your garden. Then, you will feel some joy in your life.