Everyone should "think". However, one does not think in vacuum. Our thoughts are products of our exposure to other thoughts and experiences passed through the filter of our own deliberation. Philosophy is exposure to other thoughts - thoughts of people who had different experiences than us and deliberated upon them.
Employ your time in improving yourself by other men's writings, so that you shall gain easily what others have labored hard for. - Socrates
Philosophy, according to Epictetus, is deriving the rules for everyday living via rational discourse. If one fails to do this, one may find that he has spent his days living wrong.
“The first and most important field of philosophy is the application of principles such as “Do not lie.” Next come the proofs, such as why we should not lie. The third field supports and articulates the proofs, by asking, for example, “How does this prove it? What exactly is a proof, what is logical inference, what is contradiction, what is truth, what is falsehood?” Thus, the third field is necessary because of the second, and the second because of the first. The most important, though, the one that should occupy most of our time, is the first. But we do just the opposite. We are preoccupied with the third field and give that all our attention, passing the first by altogether. The result is that we lie – but have no difficulty proving why we shouldn’t.” ― Epictetus