In the early 1970s, when the tide of summer residents would go out in September, there were always young people who didn’t want to leave the Vineyard — and they didn’t have to, because there was no particular place they planned to go. Land was still relatively affordable, or their families had land, and they built themselves homes back in the woods, had kids, a few animals and a garden, and patched together a living with the usual Vineyard hodgepodge of work or self-employment.