I guess my question is, why would a person NOT carry a firearm (whether rifle, handgun, or both) while in the outdoors?
My answer to the OP's question is "all of the above, plus some other reasons".
I can remember once in Colorado when my dad got "misplaced". He'd been dropped off at a distant location, and was supposed to work his way back to camp within a few hours before dark. We were hunting elk, and he started following a group, and got twisted around a bit. We finally found him about 8 miles PAST camp from where he'd been dropped off. He'd actually circled camp while following the elk. Him having a firearm made finding him a lot easier.
His firearm that night was a rifle, but if he wasn't hunting, a handgun would have served the same purpose.
So a firearm can act as a signal device if you're lost, injured, or are otherwise in trouble.
If I had a dollar for every critter I've turned into camp meat with a handgun, I'd be some better off.
So...
A handgun is a useful tool that can save your life, or at least make your living in the outdoors easier and better. Like a good knife, I carry a handgun with me pretty much always. Their uses are many, and I'd not be without either.
Daryl