I would guess you'll find pretty much everything. Certainly I have met a lot of teachers out there in the summer. And of course a lot of retired people. And many students who have just graduated and are taking an opportunity between school and work. You also see a lot of people in high-turnover professions (e.g., telemarketers, nurses, retail, hospitality, fast food, child care, accountants, consultants, sales, delivery drivers) who have quit their prior job and plan to look for a new job when their tour ends. And you see a lot of people who were laid off and are seizing the opportunity. Others are long-term travelers, who live very frugally and manage to stretch a small pot of money out for a long time.
A lot of the explanations, however, are simpler: they are lawyers, doctors, engineers, people in business, financial analysts, scientists, cubical workers, etc. who are simply taking a break from their jobs. If self-employed, they have arranged with others to cover for them, or if employed by others, they have asked for and been granted an extended time off.