Explosive threats are very real. Nearly anyone with enough patience and an internet connection can get on Google for a few minutes, go to the local big box store with a buddy, enter and exit through opposite doors, take a few simple precautions to obscure their visual recognition, make two separate purchases, and essentially turn those purchases into a highly effective energetic material.... and then use it to really clean someone's clock.
The problem (from a user standpoint) with many of the easily synthesized explosive compounds is that they are *HIGHLY* sensitive and unstable. This amplifies the need for a few simple procedures that many in the public safety field (from security personnel to sworn LEO's) either ignore or simply have not been taught.