Building a family and career takes all our energy. There is almost nothing left over. Our young adult years (from 20-40 for most people) are completely consumed by success at work and home. Building a life is extremely hard work.
For most of us we have had to lay aside any personal dreams that we once had to focus on survival and success. After decades of denying our dreams the bill comes due. It is normal to view our young adult years with resentment for the sacrifices that we have had to make.