Look at is as a thought experiment.

Assume we have 100 people with comparable physical abilities and knowledge. We give 50 of them a BOB (same stuff in all) and the other 50 we give nothing but the clothes on their back. We then spread them across a sufficiently large area that they are alone.

While some of the unequipped people may well survive, there are huge obstacles they must overcome relative to the BOB equipped group.

1. They have to forage for their first meal.
2. They have to find a water supply.
3. They have to not become sickened by said food/water
4. They have to construct shelter (and do it without tools)
5. They have to do all this during times there is enough light

Even assuming an extremely benign environment, the difficulty in overcoming a lack of basic tools is huge. I would venture to guess that having a BOB would give the 'average' person at least an equal chance of surviving as the most fantastically trained expert who had no gear.