Liz, that is an excellent question!! I use Linux and almost every program as well as the OS is opensource and also without cost to me. I figure these folks must love what they do. My part is to donate money and to take care in reporting bugs.
The community around all this software is another aspect that I have participated in, more in the past when I felt more competent to help answer questions of newbies, recalling the help I got when I was a linux newbie and needed help.