The main danger of hatha yoga is not to break your neck, your knees, your lower back.
The main danger of hatha yoga is to increase the attachment to your body.
You will be more flexible, but the goal is not flexibility.
You will have good health, but health is not the aim.
The goal is to relax, to release your tensions, to forget your body and ultimately, to get rid of your ego, an to realize your connection with the Whole, or God.
Dont practice yoga for finding an identity, exotism, friends or to escape from your culture.
Dont practice yoga to make thicker the wall between you and the rest of creation.
Practice yoga to developp love and compassion.