That's because Novel got wrong model, trying to make money on open source. They might be going as a company really soon.
But it's completely not true for the rest. Opensource started by students, ie then you don't have money and not willing to pay any.
Just imagine: you don't have money. You parents don't have money. $10 can help you to live for week. But you like computers a lot. You would still play with it, "share" commercial software with your friends, write your own or modify other opensource projects. Don't forget that most popular kubuntu came from Africa. How many more examples do you need?