If the world was made of peanut butter then everyone living in that world would get fat.
Also everyone would have terrible acne from being covered in peanut butter all of the time
The ones allergic to peanut butter would probably die The ones who do not like peanut butter would probably die of starvation. Yeah companies who sell those acne products they would probably get rich too
Problem is that the acne products would also be peanut butter