I think she has done some incredible work. People either like her or not and her work does not seem to sway anyone's opinion so I think she does it because she cares.
en.wikipedia.org/wiki/Angelina_Jolie
"Jolie first personally encountered the effects of a humanitarian crisis while filming Lara Croft: Tomb Raider (2001) in war-torn Cambodia, an experience she later credited with having brought her a greater understanding of the world."
"... she donated $1 million in response to an international UNHCR emergency appeal, the largest donation UNHCR had ever received from a private individual. She covered all costs related to her missions and shared the same rudimentary working and living conditions as UNHCR field staff on all of her visits."
"In May 2012, Jolie joined UK Foreign Secretary William Hague in a campaign against sexual violence in military conflict zones, the Preventing Sexual Violence Initiative. To highlight the problem, Jolie and Hague subsequently travelled to eastern DR Congo, where rape has been frequently used as a weapon of war by rebel groups and soldiers. In 2013, she spoke at a G8 foreign ministers meeting, where ministers pledged $36 million in funding to go toward developing international standards for the investigation and prosecution of war rape, and before the UN security council—the UN's most powerful body—which responded by adopting its broadest resolution on the issue to date."
If she was just doing it for the publicity I can imagine she could get a lot more publicity for a lot less expensive and potentially dangerous activities. I don;t know her but I think she cares and is an incredible woman and role model.