Sure a lot of charges are pure instinct. I'd say the vast majority of the time, that Hog is going to take off for the hills (or the deep brush). It's those exceptions you have to watch out for. My training in the military always comes to mind, if you are ambushed and there is no place to run and no place to hide, you only have one option left, "charge".

Hogs are about 50% predator, predators of opportunity.

I expect them to run, but I always have the thought in the back of my mind, maybe they won't. I've seen what a pack of Hogs can do to a Deer carcass, I sure as heck don't want to be that Deer carcass. Sure in most cases their first instinct is escape, but some have figured out they are one of the baddest Mofo's in the woods and act accordingly.

Not really relevant but somewhat. If they aren't afraid of me, I'm afraid of them. A little fear will keep you sharp and is a survival instinct. Also don't underestimate their powers of reasoning, I've been really impressed on numerous occasions.

I've watched a wise old sow lead her pack on a path that keeps them as far as possible from all the shooting towers.

I was on guard duty over a freshly harvested Strawberry field, with a truck load of strawberries ready to be picked up. The Sow lead the pack in to raid the Strawberries during the worst storm of the summer. And to make matters even worse, a big old Boar with his testicles dragging the ground followed the sounder. The last thing on my mind was climbing down that tree and arguing with that Sow (or Boar) about those strawberries. It is raining so hard I couldn't see 15 feet even with a high power flashlight. This wasn't an accident, this was a plan.

I went hunting for Roe Deer in the Czech Republic. I'd been there a week and my guide trusted me enough to send me out on my own. Maybe a two mile walk to the shooting tower and I'd left early (maybe 2:30 AM) so I could move slow (mid summer sunrise was early). Right in front of this summer mansion (multi-million dollar summer house way out in the middle of nowhere) with a large corral out front, I hear this god awful racket coming through the woods. I decide the best place for me right then was on top of the gate post for the corral. Biggest sounder (pack) I'd ever seen, maybe forty grown adults and double that counting first years and squeakers (if anything I'm under estimating). The head sow walks right up near my fence post and eyeballs me, no sign of fear at all. You could actually see the brain cells working. I sat there and watched them for over an hour, until they decided to move on, then I shot a straggler. I didn't get down off of that post for at least half an hour, after I was sure they weren't coming back. My guide gave me heck for not shooting more.

Side note, this corral was 8X8 rails with 14-16" posts and eight feet high. My guess is whomever owned the house had a pet Elephant. It was really bazaar.