There is nothing stronger than the heart of a volunteer. Some of the most amazing projects in the world have seen the light of day only because of the contributions of these selfless individuals. The same holds true for hundreds of open source projects from Fedora to Mozilla to WordPress. What motivates these people to become part of an open source project? Not money, or at least not only money. What benefits do these "unpaid workers" reap from their participation in such projects?
From my experience and that of friends who actively participate in these noble projects, I realized that a stretch with an open source project can become a priceless experience in a person's life. Some of the factors that motivate people and the consequent benefits that are drawn after a stint with an open source project are:
A socially responsible entrepreneurial mindset
Almost irrecoverable damage has happened to the business world because a few highly talented and highly unethical people managed to reach the commanding positions of the organizations that went down. This is one thing that in my opinion cannot happen in an organization driven by an open mindset. Yes, a project might get scrapped due to lack of financial fuel, but it cannot go down because of moral lapse by its leadership.
Volunteering in an open source project can make people create business and service offerings in a socially responsibly manner. When these people kick-start their own firms and projects, there are fewer chances that they will lose sight of the bigger picture--responsibly solving problems. After all, the foremost purpose of the entire process of business creation is to make the world a better place.
Collaboration is at the heart of open source. People volunteering in an open source project come from diverse sections of society. Many work as full time employees in other organizations. Many are students. Many are jobless and just want to keep their skill sets updated. One thing that all these people gain from an open source project is a collaborative mindset. They become more open in sharing ideas and opinions. They become more active and quick in collaboration. They get rid of the closed and hidden edges of their personalities.
Fair and a transparent mindset
The third immense benefit that an open source environment can add to a person's life is dedication to fairness. It will be unlikely that a person who has worked as a volunteer in such kind of a setting will do something to gain an unfair advantage.
Working with an open source project won't bring instant riches in your life, but it can give opportunities to positively transform your character and thoughts.