I think all values, measurements of worth are all in our heads. That there is no such thing as an objective value judgement, they're all a product of our subjective context and awareness.
Learn what a person values and it's easy to see what and who they are.
But it's all just shadows on the wall, and you choose to value or not value something. Those values can be dictate by others, but you choose wheither or not to accept those valuations and you're responsible for the consequences of that choice and the actions you take because of those choices. For all that values may be shadows on the wall, what you do because of those shadows are very real.
A man who rises in the morning, and believeing that it makes a difference to thank the morning and all that is for another day of existance will act and produce very differently than the man that curses, with a complete sense of his own futility, another day to survive.
Which will you choose? With each step, each breath, and each work of your life?