If a person (a) has the freedom to act as they will and (b) understands what is in their own best interests, why would they act in a way that is contrary to tho

If a person (a) has the freedom to act as they will and (b) understands what is in their own best interests, why would they act in a way that is contrary to those interests? When someone says, I really want to stop spending all day on Facebook, but I find it difficult, what do they mean? Where is the difficulty? They aren't confused about what they want. You might say they "like it" too much to stop, but what is liking something in that way if it isn't a constraint on free will. Besides which, psychology and neurology tell us that most of the time we haven't a clue what our underlying motivations are[0]. We do not have the ability to introspect our unconscious motivations, but that doesn't mean they are immune to external influence and manipulation. [0]: https://en.m.wikipedia.org/wiki/Introspection_illusion#Unreliability_of_introspection https://en.m.wikipedia.org/wiki/Introspection_illusion#Unrel...