For comparison sake, I look at what I would take on a backpack trip for a week, assuming near total environmental independence (ie I will pack everything I will need to survive except all the water I will use). I've yet to build a pack that weighs less than 50 lbs that will go anywhere I want.

As a comparison, my camelback motherlode weighs in at just over 25 lbs, and contains enough to keep me going for at least three days (including enough water, food, and emergency clothing and shelter). There's of course a big difference between just getting by and living comfortably, which is why the backpack weighs twice as much as the motherlode pack. The nice thing is that my EDC is robust enough and I am skilled enough with it that I don't need to bring the kitchen sink to get by. So really, except for the water, the BOB is not that much value added, more creature comfort.
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The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)