Learning to influence sure has its place in the human skill set. But I wonder if such skills coming from books tailored to teach about manipulating human behavior won't actually diminish individuality. Take negotiating, for example. I never really understood those people who negotiate just for the sake of it. If you set your mind on the conditions that are favorable and accessible to you, then simple honesty can go a long way. You state what are your conditions to the other part and discuss transparently how to get there. Apparently the capitalist way seems to intoxicate people by bringing the necessity of deception down to human interaction. Like if winning for your side in a transaction requires a perceived loss at the other end. Anything that you learn about human interaction in this sphere might only diminish your individuality and distort your values. If there's is one valuable lessson from such literature is on how to spot and dodge manipulators of human behaviour. Real honesty is the value that I think is mostly underrated and needed in every human relation. I doubt you will see a whole section on honesty in such books. I can't remember reading about it on the title by Dale Carnegie.