The documentary 180 Degrees South chronicles this dynamic well. You have 10's of thousands of bumpkins moving thru life for the next adventure. All the while, they never develop any form of stability, roots, sense of home, or savings. They end up social burdens as they age. It's actually a pretty miserable existence, I just don't think they see it.
At the risk of making a gross generalisation, I think that a lot of younger people today are looking for "meaning". They want to have meaningful, interesting lives.
For some, of course, that means having a house, a mortgage and a family but doing things like volunteering, much like their dad might have done through Rotary or the Lions club, but younger people would generally want to choose something more exciting than Rotary or Lions so they'll look for a charity that raises funds for Bhutanese orphans or Sumatran orang-utans or something similar.
For others, it means not being tied down to what they view as a hum-drum life. They're searching for the next big destination, the next poverty-stricken country where they can live cheaply.
Of course, this isn't new. Back in the 1950s and 1960s, such people were called hippies or drop-outs. It's just become a bit more mainstream now and is viewed as a viable life choice by some younger people.
With the internet and mobile computing allowing people to work remotely, it can be possible for people to earn a living while they travel, depending on their work. I've known some people who've lived on small islands in SE Asia doing freelance translation work - they can live very cheaply and, as long as they have an internet connection, it doesn't matter where they're located.
I do agree that a substantial number of people who choose this lifestyle will end in their mid-30s with no career, no house, no roots. Sure, they've had a heck of an adventure, but they then find that they're a decade or more behind their contemporaries if they choose to come back to a more conventional life.
