two verbs in one sentence?

Could you paraphase the following sentence for me? A lot of thanks!
"Computer-education advocates forsake this optimistic notion for a pessimism that betrays their otherwise cheery outlook."


RF: http://www.yeworld.net/index/17_20011225/17%2020011225170146%20111.asp
the context:
An invisible border divides those arguing for computers in the classroom on the behalf of students' career prospects and those arguing for computers in the classroom for broader reasons of radical educational reform. Very few writers on the subject have explored this distinction-in-deed, contradiction -- which goes to the heart of what is wrong with the campaign to put computers in the classroom.

An education that aims at getting a student a certain kind of job is a technical education, justified for reasons radically different from why education is universally required by law. It is not simply to raise everyone's job prospects that all children are legally required to attend school into their teens. Rather, we have a certain conception of the American citizen, a character who is incomplete if he cannot competently assess how his livelihood and happiness are affected by things outside of himself. But this was not always the case; before it was legally required for all children to attend school until a certain age, It was widely accepted that some were just not equipped by nature to pursue this kind of education. With optimism characteristic of all industrialized countries, we came to accept that everyone is fit to be educated. computer-education advocates forsake this optimistic notion for a pessimism that betrays their otherwise cheery outlook. Banking on the confusion between educational and vocational reasons for bringing computers into schools, computered advocates often emphasize the job prospects of graduates over their educational achievement.