I definitely think that gap years are a benefit of wealthy students. It is something that some other students do not have the luxury of being able to do. Obviously, some of those reasons are because of money and time. I think that it is clear it is about somebody's financial means.
Yes, gap years are a privilege of wealthy students. I believe that students from poorer economic backgrounds do not have the luxury to indulge in a gap year. They usually need a job or financial aid while completing their education and cannot afford to take time off to discover themselves or take a break.
I think they mostly are. Lots of poor students are not financially able to take a year off without earning money. Most of the countries that gap year students like to visit, prohibit visitors from working in those countries. The air fares are also expensive, and a year of accommodation adds up as well, no matter how humble.
Wealth makes many things easier; going to school, changing jobs, sloughing off for a year while you decide if you are going to bother getting educated or just leech off your parents. There is nothing in the way 'gap years' are taken that prevents anyone of a lower income bracket from participating. While having little-to-no spare money available from parents or other relatives means that full participation is more difficult, no haring off to China for a month as an example, you can still take that time to explore the world closer to yourself and decide how you want to move forward with your life.