You answered it yourself. Github gets money to stay alive, and resources and leadership to actually start building again.
And if so, then were open source to move toward GitLab with their even more permissive policies, how could they avoid the same fate?
It's more about having too many people working on non-core products that don't deliver value. Gitlab seems to be doing fine and has built a full-featured CI system in the same time Github has only managed to add a basic project board and include commit messages in search.