A correspondent writes to ask about the noun use of tragic, as in a Beatles tragic or an opera tragic, where it means 'someone who is intensely interested or absorbed in a topic'. She had used it unconsciously in a message to a US colleague, who didn't understand it, and she wonders how widespread it is.
My correspondent is from Australia, where it's quite a common usage - for example, all the instances of opera tragic I've found on Google come from Australia. A site called cricket-blog is headed 'a blog where an Australian cricket tragic talks Ashes' and goes on to say that this is the place 'where cricket tragics rant'. I've never come across the usage, singular or plural, outside that variety. I'm not surprised her American contact didn't get it. A British contact wouldn't have either. I've no idea if it has any usage outside Australia, and perhaps readers of this blog would let me know if they've encountered it elsewhere.
How it developed this meaning is a bit of a puzzle. Presumably it's like the reverse semantic shift we find in such words as wicked to mean 'great'. But when and how this shift took place with tragic isn't established. There are no references to the usage in the OED. All the noun uses of tragic there are related to the traditional meaning: the earliest use, in the late 16th century, meant 'a tragic actor'; then it was used for 'a tragic author'; later, it came to mean 'a tragic work of some kind' or 'a tragic event'. We find such usages as That was a miserable tragic and all the tragics you can think of. But all these earlier (and now obsolete) usages maintain the traditional sense of tragic.