The information in books is not tailored to your circumstances and individuality; it tends to be somewhat abstract. When you are young and have less experience of the world, this abstract knowledge is hard to put into practice. You can learn from your experiences, but it can often take years to fully understand the meaning of what has happened. It is always possible to practice on your own, but you will not receive enough focused feedback. You can often gain a self-directed apprenticeship in many fields, but this could take ten years, maybe more.
