I collect what makes me happy. That is really all there is to it. It was my philosophy when I collected model horses and it's the same for my anime figures.
I do the same, and I collect a lot of things. The last thing I am thinking about is resale value.
Current Collections
One Piece POPs
One Piece Manga Volumes
Star Trek Starships Collection
Star Wars Lego Starships
My Little Pony Funko Vinyls (Joint collection with wife)
Lucasarts Adventure Games (The ones in the big boxes)
Previous Collections (Either sold or given away)
One Piece Grandline Series
One Piece Stylings
Star Wars Starships and Vehicles Collections
Lord of the Rings Models Collection