Nothing at all. However, it takes immense fearlessness, even fierceness to live an authentic life. Many people live lives on others' terms because of the element of fear-fear of disapproval, ostracization, & even marginalization & abandonment by family members, friends, peers,, & associates. Most people DON'T want these types of disapproval at all so they would rather lead a gray, toxic inauthentic life than to lead a red, joyous, authentic life of passion & ownership.
Also, leading an authentic life on one's own terms means having a sense of power & ownership. Many people are quite afraid of these things. They refuse to acknowledge that they have power & ownership, being inculcated early that these words are somehow self-aggrandizing. They were raised to believe that it is FAR BETTER to give their power & ownership away to person "more authoritative" than they are. People who are aware of their power & ownership are viewed as very problematic, even threatening. They are considered to be unmanageable. The main emphasis in many people's life is to be totally conforming.
Those who lead authentic lives of power & ownership have faced ostracization from others. However, they continue to persist in their goals. The ones who lead authentic lives oftentimes are healthier physically, mentally, emotionally, & psychologically than those who lead lives that others prescribe for them. Those who lead authentic lives are living to their highest potential & their dharma. They also have NO REGRETS as opposed to many people who have MASSIVE REGRETS for living the lives that others dictate.