See the lead singer of Cannibal Corpse Corpsegrinder who donates to children's charities all the time
And also gets all giddy when Walmart has a clearance sale:
And enjoys playing claw machines while swearing in foreign languages:
George is such a nerd sperg goofball in private it's kinda funny. A very stark contrast compared to his on-stage presence.
EDIT: As for the "normal people do better with dark concepts", I think it's pretty simple.
A normal person has a functioning moral compass, so for example they know that a mass murderer child rapist is something disturbing to the viewer. Because it's disturbing to them, they know it's evil, so fiction created around those concepts will be disturbing.
A deranged person has a dysfunctional moral compass, so to them such a concept might not seem scary, because that's their actual tendencies, and if they still have the self-awareness they'll avoid such topics as they remind them that they're the dregs of society and they hate it.
This also goes for how a normal person and a deranged person present themselves. A normal person acts freely, as they are. A deranged person has to act like someone they're not so their dark secret won't surface, as they look for acceptance in a society full of well-adjusted people as someone who cannot fit into it.