Kennedy refers to his audience as pathfinders and pioneers and mentions the new frontier. why might kennedy use these words

Kennedy made a comparison of his audience with the pioneers of yesteryear, who renounced their security, their well-being and, at times, their lives to build a new world,  he said they were not trapped in their own doubts or prisoners of the price of theirs labels, their motto was not "Save yourselves who can", but "Everyone for the common cause", mentioning the new frontier as a way to reduce the tax burden, with the aim of favoring investments and motivating consumption, this would be accompanied by a increase in public spending.