Camping right off a NF road; which I don't like to do, but had no choice in this particular situation. Around 3 in the morning my buddy in another tent yells "Get your gun!"....unzipped the tent with said gun, and ran out to a cars headlights pointed in the direction of my tent and about 20 feet away. Had one in the chamber and in the ready position as I approached the truck.....turned out to be a guy that passed us earlier in the day, drunk as a skunk, and driving back to his tent for the night. Told him he scared the shit out of us and that he was about to get shot. He apologized and that was that.
Other than that, I have never felt threatened when hiking on trails or in the backcountry, but I always bring a sidearm with me cause you just never know. What's the saying; "rather have it and not need it, than need it and not have it." That's my approach - especially if weight isn't an issue - and the sidearm, for me, is weight I'll always bring.
If anything, I probably am the threatening figure as I'm hiking with a loaded pack, sometimes my HPG chest rig and a gun hanging on my belt haha.