[zozbot234]

> Corporate, commercial software development, for money, and licensing software under pay-for-use terms, is how almost all software developers make money.

Most software by far is developed and supported in-house, not sold as a COTS product. For in-house software that doesn't see any broader distribution, the distinction between "open" and "proprietary" is pretty much immaterial. Even the comparatively strict GPL license allows for private modification.