Bruce Schneier points out an analysis of attempted terrorist attacks since 9/11. I think Schneier’s summary explains everything:
So few of them are actually real, and so many of them were created or otherwise facilitated by law enforcement.
Most cases of so-called terrorism involve government agents finding gullible people, egging them on to perform an act of terrorism, and then enabling those people by providing knowledge and materials required to perform the act of terror which has usually devised by the government agent. They aren’t keeping us safe, they’re creating the problem.