Some people won’t adhere to a diet that would make them healthy.
Stupidity? Yes, stupidity on a very deep selfish gene level.
It’s not that they don’t understand the price they are paying.
It’s that they make choices that the genes are making: not making waves, not bringing attention to themselves, not being different, fitting in is more important than being healthy, having energy, feeling good, calm, intelligent.
Almost everything “social” is gene directed. I say “almost” because I am humble. I don’t know any social that is NOT gene directed, but there could be, maybe.
So what do the genes want?
The genes want to survive, and they want to pass into a new generation.
Being liked, fitting in are
As you already know, I consider the root of all evil a conspiracy: consciously misleading, consciously training you to be a zombie, so they can harvest your money, so they can harvest your power for their own purposes.