Fame
While your name will never be recognized outside of development conferences or human rights academic programs or the halls of government, it is possible to garner fame as an international aid worker…not that this career field is about becoming famous.
Take Paul Farmer, for example. Every development student you'll ever speak to knows who this guy is. He founded an organization called Partners in Health that went after the scourge of HIV/AIDS in Haiti via the accompagnateur program. Essentially, PiH trained thousands of Haitians as community health workers who could monitor and deliver health care to the sick. Farmer's innovative method for getting health services to those in need has been replicated by other organizations around the world.
But let's be realistic: Most international aid workers are never going to be Paul Farmer-famous, and that's okay. Fame isn't what this career field is about.