Why is there a stigma attached to mental illness?

If we interact with people around, you will see that they have vague ideas about psychological disorders that are characterised by superstition, ignorance and fear. Again it is commonly believed that psychological disorder is something to be ashamed of. The stigma attached to mental illness means that people are hesitant to consult a doctor or psychologist because they are ashamed of their problems. Actually, psychological disorder which indicates a failure in adaptation should be viewed as any other illness.