In the childhood, we have many questions and only a few answers. Though, the child itself is not the subject matter of any questions. It is a child and everybody accepts its poor knowledge in spite of its inability to give answers.
The grown up persons who seem to be fulfilled in the social order are recognized through a similar lack of questions about them. They are clearly workers, teachers, politicians, and so on. We may ask them about what they do, but not about who they are.
The idea that they have answers to the essential questions about their life is false. Their fulfillment is not due to a perfect knowledge of life. They simply cannot put under question their social status they have assumed, but that status is a way to stand apart from the tumultuous and changeable course of life which gives birth to questions and doubts.
Therefore, an immature kind of life can also be attributed to those serious people who believe that they reached the maturity of their life in the social order. The playful habits of serious people (the modern technology highly increased their number) are not strange. They release that immaturity and keep the people from the awareness of the doubtful nature of life.