I would say tool and a therapist. A tool in that they put food on the table (sometimes.) I probably take better care of them than most of the things I own.
But, they are therapy. My job is often times pretty high stress. I find them relaxing. I almost exclusively shoot muzzleloaders. If I don't shoot one of them I shoot a revolver and if I were to ever buy another centerfire rifle it would likely be a single shot. They force me to slow down and take my time. Shooting semi-autos always turn into how many rounds and how fast. I've thought about putting muzzleloaders down for a few years and trying a bow. But I think I would miss the smell of the smoke, the pull of a trigger, and in general the way a rifle feels.