It depends on where they are and how entrenched their family is in that area. Visiting professors sometimes come from industry. They get tired of the grind and want to settle down, and they hope to get offered a tenured job with all its benefits (great pay, tuition benefits for their kids, etc). Or maybe they’re here on a visa and are hoping they’ll get sponsored so they can stay. Adjuncts tend to be people who already live in the area and who either have a full time job elsewhere or they’re retirees who are supplementing their income.