[Reinmar]

It was even worse for CKEditor:

> From these thousands of businesses and millions of downloads, a very small group (less than 0,5%) decides to enter into business relations with CKSource.

Source: https://github.com/ckeditor/ckeditor5/issues/991

However, the difference is that all CKEditor 4's plugins were open sourced and licensed under a permissive set of GPL2+/LGPL/MPL licenses. So the project was funded by a combination of support, SLAs and commercial licenses.

With CKEditor 5 (a completely new project) we chose GPL2+. I will be able to tell you how it worked for us in a couple of years