<< people are willing to do things for free with almost no real motive behind it other than they want to make some cool software. It's beautiful. >>
As much as we would like to think that all Open Source and Free Software programmers are selfless martyrs, there really is a great variety of reasons why people contribute to this cause.
First and foremost is the love for software and the desire to make cool software, and the desire to share one's cool creations with others. Programmers hate having to limit the reach of their creations by using limitations such as having a price on the software, etc. So they make their work available under the GPL, which guarantees that the work, and all derivatives thereof, will forever be Free and free.
Secondly, is the belief that everyone is entitled to a satisfying computing life regardless of his or her financial status. This is especially poignant in third world countries, where a copy of Adobe Photoshop may cost more than a man's annual salary. Everyone is entitled to a good, stable operating sytem, a good, functional office suite, art tools, programming tools, etc, etc, for free, so that they can use these tools to further themselves in life. It costs absolutely nothing to distribute these tools once they are made, and it makes such a great difference to so many underprivileged people, that this is a very worthy cause.
Third is the belief that Free Software and Open Source software increases efficiency, code reuse, turnaround time, stability and collaboration. When everyone has access to the source code, everyone can chip in what little support they can contribute, and each and every little bit makes a difference. Even a code audit or a bug report makes a difference when a thousand, ten thousand, a hundred thousand people like you take ten minutes out of their day to make an Open Source program better. And the GPL guarantees that what is Free today will be Free ten years from now, and all the contrubitions and improvements that have been made to the program will also be Free.
Fourth is bragging rights and resume building. A well-written Open Source program spreads much faster than an equally well-written commercial program, because there is no financial barrier to entry and use. Anyone who acquires a well-written Open Source program can also study the source code and admire your genius, possibly even offer you a job! Every Open Source project you release into the wild is like a very long, very detailed resume that showcases your skills. It adds to your employability and imbues you with a very positive reputation in the Information Technology community.
These are some of the more important reasons that I can think of off the top of my head as to why so many people are so dedicated to the Open Source and the Free Software movements. There are doubtless other reasons. But the fact remains that this development philosophy and technique is so superior to the traditional in-house proprietary software development techniques, that in the short term, proprietary software vendors must either adapt to the changing times, or they will surely die.