The consensus among historians is that the Vietnam War killed the Great Society.
When Pres. Lyndon B. Johnson pledged to create a "great society" and to wage a "war on poverty," it was clear that these goals would take a huge amount of spending on the part of the government. If the government was going to be able to commit this kind of money to fighting poverty, it had to avoid excessive spending in other areas.
This was not to be. As Johnson's presidency went on, the war in Vietnam expanded and became more expensive. As this happened, it became harder and harder for the government to afford all of the programs of the Great Society. In addition, the problems of Vietnam helped force Johnson to forego running for reelection in 1968.
Between the lack of money and the fact that a Republican, Richard Nixon, was elected in 1968, the Great Society was doomed. Therefore, most historians say the Great Society's decline was caused by the Vietnam War.
In his campaigns, President Lyndon Johnson stated that it was for the interest of the nation to support a social reform order also known as the Great Society, for the purpose of facilitating poverty eradication and social equality. Apart from poverty eradication and social equality, he promised to improve on education, environmental protection and improvement of the cities. The Great Society required a vast amount of resources to be successfully implemented, with other competing needs and engagements, the President’s visions were becoming harder to fully implement. Programs initiated by the Lyndon administration succeeded, such as Medicare, which improved health access or senior citizens, others including federal funding of education and Urban renewal were also implemented. However, the engagement in Vietnam brought about considerable financial challenges to the full implementation of the Great Society, eventually, leading to its disruption. Military expansion and loses in Vietnam led to the drop in public appeal for both the administration and the programs it initiated.