“They are until they aren’t.”
Up in Alaska they say that the Grizzlies will attack you if/when they think you are a threat to their food, and it is best to cover your head and neck and play dead if you can’t reasonably defend yourself.
Black bears mostly attack because they somehow think you are a threat to them, or they are just plain “mean”. And you should fight them as best you can but they probably won’t quit until either you or the bear is dead.
Cougars mostly attack because they mistake you for prey, and if you fight them (even punching them) they will often take off.
I imagine for all three, all bets are off with their cubs are around. This is just advice I’ve heard - and hope I never have to put it to the test. Most of the time they want to stay far away from humans.
There was this mountain lion attack earlier this year. https://www.kuow.org/stories/cougar-attack-washington-state-cyclists
No grizzlies where I roam, and i’ve only seen a couple of black bears which ignored me. I don’t expect to be attacked by a mountain lion, and I’ve never seen one, but if I ever do get attacked by one, I figure it will be by one i didn’t see.