Reason 1: Adolescents identify their own value and worth in terms of their social group. Teenagers in America, in Ethiopia, in Antarctica think in relation to peers. Most of their thought is consumed consciously or subconsciously by "what do I have to do to become more popular." So, the pressure of being an adolescent is great, but the pressure of being an adolescent immigrant is insurmountable. You don't speak the language of the others - and this is not only the English language but also the slang and moreover, this is not only verbal language but also physical language. There are a lot of dances, facial expressions, silly movements and other mannerism that are learnt over a long period of time. So, this adolescent immigrant becomes not only a foreigner to the country, but more importantly a foreigner to the other kids at school or in the neighborhood, a foreigner to friendships and groups, and eventually a foreigner to him or herself because an adolescent's understanding of oneself is in terms of social networks.
Reason 2: when we encourage the idea that America is the golden land of opportunities and the place where dreams come true, we deceive our people and our young children. America is a wonderful country, no doubt. Opportunities, however, can be found anywhere just as long as your eyes are open to them. When we encourage young Ethiopians to dream about coming to America, we enable them to close their eyes to opportunity and we cheat them out of the opportunities available in Ethiopia. Let us act to stop this violent spread of wrong information; America is great but so too is Ethiopia.
Reason 3: this is a more macro analysis but, nevertheless, Brain drain. A nation's one greatest asset is its people; and Ethiopia is losing a fortune.