Sally first said the landing was a waste of money, like the football player, but after talking to Don and looking into the telescope with the other boy she choose not to be cynical by kissing the nerd boy. She was drawn in by the wonders of the universe and life rather than being sucked into the importance of money and who she is supposed to become (Don)
"The best things in life are free"
Joan, Cutler and Harry seem to be motivated by money and greed while Don, Roger, Ted and maybe even Pete are more driven by self-actualization at this point in their careers as their personal lives are mostly in shambles.
Who knows what happens to Draper in the end.
