Terminally ill patients may feel that they are a burden on society and an unnecessary financial drain on their families. Most people feel that it is morally wrong to exploit others, especially those who have treated them well in the past. This attitude encourages terminally ill patients to try to end their life.
On the other hand, accelerating one's own death is viewed as immoral or sinful in many cultures, and requesting help from others to die can seem even more morally repugnant. In addition, most people simply want to live. These factors discourage people from taking their own life.