This question assumes that there was some leader of the hippie movement and that he influenced people to follow him. I do not believe that this is true.
The hippie movement did not have any acknowledged leader or anyone who is credited with starting it. Instead, it is seen as a result of societal forces that were present in the United States at the time. These forces influenced many (but by no means all) young people to become hippies to some degree.
The most usual story is that the conformity and materialism of the the 1950s generation turned the next generation off. They (it is said) wanted to live in ways that were more spiritually meaningful to them. They wanted to do their own thing rather than to obey what authority said. In this way, they were rebelling against what they saw as the empty lives their parents were leading.
So it was a general social trend that influenced people to be hippies -- not one person who was leader of the movement.
In relation to the hippie movement, one of the most profound influences that Dr. Leary had on the counter culture movement of the 1960s was to stress that individuals needed to "break on through" past that social conventions that had a hold on society. Leary stressed that the best way to do this was to enhance one's own sense of being in the world and this altering of consciousness could be experienced through the use of LSD. While Leary's encouragement of drug use played a large role in the hippie movement of the time period, his impact was more than this. The idea of creating a culture that defined itself against the powers of conformity, the notion of establishing a social order that truly wanted to construct society from what is to what should be, and the idea that individuals had a duty to destabilize social orders that emphasized material acquisition and replications of power that silenced voices all appealed to the movement. At this point, Leary had done an excellent job of providing the basis for a social revolution where young people were able to distance themselves from the need to conform.