Running is, at times, a selfish pursuit. That said, I love the solitude, the quiet headspace that a run alone provides. For me it's essential, and no less selfish than, ah, attending two or three football matches a week *cough* or reading a book in another room for an hour or two. Balance is the key.
Anyway, you don't have to leave home for too long to train for an Ultra
The harder the conflict, the more glorious the triumph