Most people I talk to who are in their 30's are in love with the idea of having a treehouse to retreat to - seems like most of my friends daydream about just such a sanctuary.
Keep working friends and perhaps you can afford one of these treehouses that are designed and built for full-time living.
See FC: Architecture Firm Specializes in Bespoke Treehouses
Official site: Amazon Treehouses
Rather build your own treehouse? Check out the Northwest Treehouse School in Fall City, Washington.