To plan your life (especially by following a career) does not mean to have a rational life. Because rationality is known even from the first acquisitions of knowledge as a restless questioning.
There are put questions which finally derive from the different states of things and human experiences. And all such questionable facts occur in an organized life, too.
Therefore, the answers of those who plan their lives cannot be fully rational. In virtue of their habit of planning, they will organize the questionable facts as if they would not need to be questioned, but only to be moved in certain patterns.
And because such kind of people generally organize the life of the entire society, the really rational people will ever find reasons for raising questions. Surely, with the risk of losing a stable place in a society which does not belong to them.