The obsession of a "crazy cat lady" mixed with the entitled princess attitude of the little girl who actually got a pony for her birthday.
That said, it is a hobby that desires a lot of time and/or money, plus dedication, so if anyone is involved in the hobby for more than a month it is, by necessity, going to take up a large part of their life, often at the expense of other things (you, date night, etc). If you understand that the hobby is one of the most important things in their life (or share the hobby) and go with it then you'll be okay.
A more commonly male example I'm familiar with is salt water fish tanks. They become an obsession, because one has to micromanage so many parameters correctly or they kill thousands of dollars worth of livestock that took years to grow, and if one has the means they eventually knock down a wall and fill up half the garage with fish tank.