A person who is obsessed with guns is often referred to as a "gun enthusiast" or "gun aficionado." In some contexts, they might also be called a "gun nut," which can carry a more negative connotation. Such individuals may collect firearms, engage in shooting sports, or advocate for gun rights and culture.
Some people call us "gun nuts". I call myself a collector.
Racist
Morbid.
lexicologist.
It could be a chronophile (one who is obsessed about time).
Custy
crazy cat person
A person that loves all things French might be called a Francophile.
It is not good to be obsessed with ANYTHING.
Gun Dealer
Well it depends. If you're a man and you're obsessed with another man well it's called being gay. And if you're a girl and you're obsessed with men it's called love!
A person that hunts dinosaur bones is called a paleontologist.