Two historical examples: The Weather Underground regularly and the IRA occasionally called in their bombs in advance order to reduce/remove civilian casualties. They tried to give enough time to evacuate an area but not enough time to find and defuse the device.

I wore all black as a high school student. It fit with my subculture intersts and I just dug the dark aesthetic. I knew other people found it to be unsettling but figured they should probably be more open minded and judge people for what they do and say rather than how they look... I was right, too. Cops disagreed. The nice part is how pleased people were to find out how pleasant I was to talk to.

I suppose some people might just want to destroy infrastructure and not kill people directly (give people an opportunity to evacuate).

The replies have reminded me to mention that I shouldn't judge so quickly and that a handful of those all-black-clothes-all-day-regardless-of-weather school mates were and some still are my friends. I still believe there is a message that is trying to be delivered via one's threads but it can be a plethora of messages rather than just "fear me". EOM.