Why do people get claw toes?

Let me explian. The muscles that control your toes get out of balance and cause the toe to bend into an odd position at one or more joints. These toe problems almost always happen in the four smaller toes, not the big toe.
Type of hammertoe. People can get hammertoes several different ways, including just an unlucky roll of the genetic dice, but the fundamental result is usually the same: a toe that has drawn back and no longer sits straight or "flat". Sometimes it's only a tendon that holds the toe in that position, other times there's arthritis involved: these tend to be more rigid, and require surgery if you want them corrected.
Several causes. A clawtoe is an abnormal contracture or a bending of the toe joints which results from a muscle or tendon imbalance due to the mechanical and structural changes in the foot that may occur over time. This can be hereditary or due to environmental factors such as tight shoes. This abnormal bending can lead to abnormal pressure distribution resulting in pain, swelling, blistering, and corns.
Claw toes. It usually due to compensation in your foot. Typically you might have a tight calf muscle and the muscle in front of your leg are trying to flex your ankle against a tight calf muscle. So with the constant over pulling the toes start to curl up this creating a claw toe.