It's not unique to software.
Go to any play or recital, and the program will have an entire page devoted to donations -- big companies up at the Platinum level, medium companies and rich folks at the Gold level, on down to random folks at the $0-50 level. Until you get up to the Hollywood movie / arena rock level, art always operates at a loss.
Hospitals and universities also frequently have wealthy patrons. I'm sure there are other fields, too, that I'm forgetting or don't know about.
Solving this problem for the field of software would be very cool, and it's always a great idea to start with one particular domain. The big picture remains: how can people continue to do good and worthwhile work, when the economics aren't on their side?
I know many people doing work they hate, and which isn't in any way worthwhile, just to pay their bills. When I was younger, I worked for 2 years on a "death march project" that never shipped. I was young enough to not realize that I couldn't make a difference. The older and more cynical people knew all along it would never ship. The Invisible Hand can't always deal with the complexities of modern life.
I'm not even convinced that money is part of the answer. I don't care about money, except in that I need it to pay taxes, rent, health care, and so on. Maybe I watched too much Star Trek as a kid, but it feels like a post-scarcity world shouldn't require citizens to worry about cash, unless they want to do something especially extravagant.