We have a regular group who get together once a week for RPG and the previous campaign started in '99 and finished early this year. The players changed over the years as people moved away or lost interest or had other commitments. And new players joined and the DM continued with an epic campaign, modifying it to add different PC hooks as the characters changed. In the end a lot of the NPCs in the campaign were old PCs of players who had left the group.
So, I'd have to say that I'm a role rather than roll player. Sure, throwing some dice is fun, but that doesn't keep you coming back to the game, IMO. A fantastic DM helps too