I hope I'm not quoting you out of context. But I firmly believe the equation is a lot more compex than that.

Humans, more often than not, project the 'body language' of Predator, not Prey. It's not necessarily about our size, or strength (physically, we're quite unimpressive). But (as one highly experienced author suggests) this protects us in a lot of situations where (based on strength and body weight) we would otherwise be obvious and easy food sources.

To that end, I think most bear attacks are in fact defensive (taking out a rival or threat, or protecting my food source) rather than predatory (mmm, easy lunch!).

Bears, like people, are individuals, and each one will do the 'mental math' of risk-vs.-reward differently. So there are always exceptions to the rule.

Some also suggest that the 'math' in a bear's head changes depending on how you act -- that is, your body language. I believe this, knowing that the right 'attitude' physically and vocally will rout a 2,000 lb. Holstein bull who is seriously p***ed off; or that my Great Danes (two big marshmallows) can tell instantly if you are 'top dog' or 'scared to death.'