The document discusses challenges and lessons learned from interviewing 200 entrepreneurs and experts in the collaborative economy across 12 countries. Some of the key lessons include that collaborative entrepreneurs just do things with lowering barriers to start, focus on their core and get the best partners, and grow exponentially by facilitating others to create value. Major challenges include determining how to scale sustainably, ensuring models remain future proof, addressing labor issues, and improving data transparency and ratings systems. Transitioning to more sustainable models may require redefining value and success, exploring new ownership and governance models, crowdsourcing activities, and finding the right balance between old and new approaches.