Ed went to the Moon because he was extremely well qualified to fly the LM.
He was the first of his selection and chosen (and flew after Haise because Shepard wasn't ready yet) by Shepard and Slayton.
When he speaks, he's very clear and you sense an intelligence way above average.
What he decided to do after 14 was his choice alone. Everyone of the Moonwalker had a life after the Moon and for all of them, a confortable one, which meant they did exactly what suited them.
Even if their after-the-moon-life seemed rather odd, to us.