I have two real-world examples where this notion played out spectacularly:
- An ex-gf took an unpaid internship at the main museum here in San Diego with minimal job prospects upon graduating from USCD with a BA in history. 6 months later she took a full-time position at that museum, beating out someone with a MFA from Stanford simply because she was exposed to so many influential people in the industry who vouched for her. A year after that shee was promoted to managing their event planning dept.
- I transitioned from C# to Rails work by doing a pro-bono project for 4 months @ ~20hrs/week, the main condition was that they paid for a Sr. dev for mentorship. My mentor on that project continued to bring me work following that project, so much so that I quit my day job.
Value can be many things. Money is just one of them.