You are saying that comfortable communication with friends is rationally less important than long-term ideological battle that you don’t really influence?
If you don't mind sharing your private conversations then sure it starts looking rational.
It is not just an ideological battle when your information is used directly against you personally. Companies pay for ads targeted to you by mining your personal content.
If you are not on facebook or rarely use it they have no opportunity to influence you.
You can use Facebook while not having any conversations on it you'd wish to stay private. I think most of my friends still on Facebook use it that way.
Facebook is a contact point, first and foremost. Nothing prevents you from greeting a friend and requesting that the conversation continues on a more private channel.
It is a good parallel. Obviously if your relatives live on another continent, flying is the optimal, but for example you can ride a bus from SF to LA instead of flying.
