Background: Maasai are a Nilotic ethnic group inhabiting central and southern Kenya and northern Tanzania. They are among the best known local populations due to their residence near the many game parks of the African Great Lakes, and their distinctive customs and dress.The Maasai speak the Maa language (ol Maa), a member of the Nilo-Saharan family that is related to Dinka and Nuer languages. Some have become educated in the official languages of Kenya and Tanzania, Swahili and English.
Context: Maintaining a traditional pastoral lifestyle has become increasingly difficult due to outside influences of the modern world. Garrett Hardin's article, outlining the "tragedy of the commons", as well as Melville Herskovits' "cattle complex" helped to influence ecologists and policy makers about the harm Maasai pastoralists were causing to savannah rangelands. This concept was later proven false by anthropologists but is still deeply ingrained in the minds of ecologists and Tanzanian officials. This influenced British colonial policy makers in 1951 to remove all Maasai from the Serengeti National Park and relegate them to areas in and around the Ngorongoro Conservation Area (NCA). The plan for the NCA was to put Maasai interests above all else, but this promise was never met.The spread of HIV was rampant. Due to an increase in Maasai population, loss of cattle populations to disease, and lack of available rangelands because of new park boundaries and the incursion of settlements and farms by other tribes (this is also the chief reason for the decline in wildlife-habitat loss, with the second being poaching), the Maasai were forced to develop new ways of sustaining themselves. Many Maasai began to cultivate maize and other crops to get by, a practice that was culturally viewed negatively. Cultivation was first introduced to the Maasai by displaced WaArusha and WaMeru women who were married to Maasai men; subsequent generations practiced a mixed livelihood. To further complicate their situation, in 1975 the Ngorongoro Conservation Area banned cultivation practices. In order to survive they are forced to participate in Tanzania's monetary economy. They have to sell their animals and traditional medicines in order to buy food. The ban on cultivation was lifted in 1992 and cultivation has again become an important part of Maasai livelihood. Park boundaries and land privatisation has continued to limit grazing area for the Maasai and have forced them to change considerably. Over the years, many projects have begun to help Maasai tribal leaders find ways to preserve their traditions while also balancing the education needs of their children for the modern world. The emerging forms of employment among the Maasai people include farming, business (selling of traditional medicine, running of restaurants/shops, buying and selling of minerals, selling milk and milk products by women, embroideries), and wage employment (as security guards/ watchmen, waiters, tourist guides), and others who are engaged in the public and private sectors. Many Maasai have moved away from the nomadic life to positions in commerce and government. Yet despite the sophisticated urban lifestyle they may lead, many will happily head homewards dressed in designer clothes, only to emerge from the traditional family homestead wearing a shuka (colourful piece of cloth), cow hide sandals and carrying a wooden club (o-rinka) - at ease with themselves. CANNOTANSWER
Question: Why would they do that?

Answer:

The plan for the NCA was to put Maasai interests above all else, but this promise was never met.