I would argue that President Johnson spent most of his time on the Vietnam War, rather than on domestic policy, because it was more obviously pressing. It may also have been that he felt that the outcome of the war would do more to determine what his legacy was than any of his domestic programs would.
It is not surprising that a president would spend more time on foreign affairs in this situation. Many people in the US at the time believed that the security of the country would truly be diminished by a communist victory in Vietnam. If Johnson truly believed this, it would make sense for him to prioritize the war. Poverty or other such domestic issues would not be as dangerous to the country and were therefore less important. In addition, the war was causing the deaths of Americans in very obvious ways. This would catch a president’s attention more than the less visible problems caused by poverty.
In addition to this, Johnson may have been thinking about his legacy. He would not have wanted to be known as the president who lost a war. Therefore, he would have worried about the war more than about domestic issues.
In Johnson's domestic polices, it should be noted President Lyndon B. Johnson pushed many civil rights legislation through Congress for African-Americans and other minorities.
President Johnson had been a schoolteacher in his early life and believed in civil rights and justice for all Americans.
The Great Society program became Johnson's agenda for Congress in January 1965: aid to education, attack on disease, Medicare, urban renewal, beautification, conservation, development of depressed regions, a wide-scale fight against poverty, control and prevention of crime and delinquency, removal of obstacles to the right to vote. Congress, at times augmenting or amending, rapidly enacted Johnson's recommendations. Millions of elderly people found succor through the 1965 Medicare amendment to the Social Security Act.
In addition, President Johnson's domestic policy pioneered America's landing on the moon.
Under Johnson, the country made spectacular explorations of space in a program he had championed since its start. When three astronauts successfully orbited the moon in December 1968, Johnson congratulated them: "You've taken ... all of us, all over the world, into a new era. . . .