But it seems you are more interested in the other travelers, and I am more interested in the locals and the locales, and neither view is more valid than the other, of course. Many of these people were much happier than my friends. They derived satisfaction from things that have made people happy for thousands of years, e.g., children, money, religion. Thinking about all these friends growing older, unmarried and childless, I shuddered the way I would watching a family stake their whole fortune on double-zero at a Vegas roulette table. I think you base too much of your impressions here on graduate students.
Graduate students are some of the unhappiest people on earth.
When those same individuals get tenure at some nice university, they tend to be quite content. Most of them even marry and have children. Being academics, they often have more time to spend with their families than other professionals. MIT may not be representative. My professors at Bryn Mawr were often quite content.