I am a user of LaTeX for about two years and I can see that almost every package which exists for TeX is free and these packages are maintained perfectly; packages are updated regularly and new packages or classes are developed when needed.
Why people do such volunteer work? How do they benefit from the time they spend on creating and maintaining things related to TeX, LaTeX and friends? Do they do these just to have fun, fill their leisure time and learn something during the time they do not work or does working on these help people to develop their own business and work?
I know that every person may have his own reason to work on open source/free softwares, but how should I answer this question and convince somebody asking such question and thinks that it is just waste of time spending time on something which has not any financial benefit?
I personally really love TeX and LaTeX and spend some of my time learning about it but once somebody asked similar question and I had no answer to him.