@Sehrish:
There is just no single good answer to what you are asking. But you may reply a mixture of factors:
1: DMG is a bridge between the Govt and the public. It can connect us with the public in a better way.
2: DMG relates with the public administration. So, it allows to serve and manage the very human resources that you have been chosen to administer on with the help of all other resources available to you.
3: One of the best service delivery is possible in this group.
4: Personal attitude, mental aptitude and your liking for this job.
5: Prestige, honour and history of DMG
6: Job Security
7: Mobility; both social and job mobility on vertical and horizontal lines
8: Not much of a Uniformed Officer
9: Any other reason you see fit