You need other people in your life who will tell you when you are wrong.
When you are your only counsel, you are susceptible to all manner of deceit and delusion.
In solitude, the voices of pride, ego, and fear are quite convincing.
It is easy to get caught up in your own ideas, opinion, and beliefs, to lose perspective on reality and to be convinced you are right when, in fact, you are anything but.
Having trustworthy counsel, people who care about you and who want to see you succeed, or at least not fail, will keep you on course when you begin drifting into a world of self deception.