A photography student's experience

One of the photography student was amazed by SCRIBUS, an free and open source software for (Desktop)publishing. He was amazed that a software available for free can do so much. He needed to document his final project so he was using scribus but he had to switch to indesign because of few issues like color reproduction. But his biggest question was "Why would someone write software and give it away free ?"  I explained him what I had doodled. Click for the doodle