>>21649758That's seen as edgy due to the fact that it's a try hard attempt at being dark without a justification. Dark things that have a reason to be dark aren't necessarily edgy, where making things that aren't dark have dark features to make the idea of "dark" or the thing different can be seen as edgy.
Shadow the Hedgehog is edgy because he's a goddamn children's cartoon character and they give him guns and a nihilistic attitude when he's just a fucking hedgehog.
Cutting yourself for attention or something is just some psychological self-pity emotional etc. shit but that's an abstraction from the norm due it being fueled by an idea.
Cutting your arm off when it gets caught under a rock = dark
Cutting yourself for a social response/something outside of physical/survival normality = edgy
But that's being somewhat loose with the definition. That's the glory of words though, they evolve along with us as a culture and species.