The vast bulk of software is proprietary.

Some software is very generic and has a 1:100,000,000 ratio between itself and potential deployments. The same linux distro can work for billions of people. This kind of wild efficiency allows free software to be viable in a bottom-line sort of way--selling books, consultations, support, etc.

Most software has a ratio like 1:1 (custom software) or 1:10000 (industry-specific stuff). Open source is just completely impossible here. People need to make money, like it or not.