It seems to me that a window of freedom is vital in our lives, a period during which we are independent of others and have no one dependent on us. Unfortunately, many individuals with a limited education and a low income do not enjoy such a window; married or pregnant in their teens, they remain dependent on others for much of their lives while raising dependent children themselves.
Most middle income Americans experience a rather brief window of freedom which typically begins with their high school graduation and ends with an early marriage or with their college degree. Those who extend their education in graduate or professional school and/or put off marriage until their thirties may enjoy a window of freedom that lasts twelve years or more.
During this period, an individual is free to focus on their education, explore personal interests, travel the world and come to appreciate their own talents, passions and goals in life. In turn, society benefits from their maturation and both marriage and parenthood tend to be more stable and less stressful. Finally, a delayed marriage limits family size, diminishing our impact on Earth's natural ecosystems.