Why is Friday the 13th considered unlucky?

This is just my guess but after innocent knights templar were murdered and then the enemies of the knights templar died or went into ruin people get freaked out thinking the ghosts of the killed will raise up and slay the guilty. It’s true the grand master of the Templars shouted something to his killers but i think it’s more telling of Templars that he forsaw something bad coming to their enemies. They Templars had vast advanced knowledge just looking at were they were imprisoned from the show The Curse Of Oak Island, you can tell they have a lot of knowledge and respect for knowledge and symbols from places and cultures that were on their crusade. Symbols Christians would not understand and undoubtedly caused the Christian Churches to kill out of fear. Only some modern people numbering about a dozen thousand would recognize the true layers and depth of their symbols. Only if they are looking for them and i only know a handful who are.

I don't think so.
Dates can remind us of bad things but that's all there to it.