I can't speak for him...

But I stopped open sourcing some of my work when I got aggressive users demanding I support them for free. I realised I was pouring hours into triaging bugs, explaining why PR's weren't good enough, fixing other people's corner cases, and settling disputes, without really getting much back. Sure, my projects were getting a following and there were lots of happy users, but the actual benefit to me of that happening was negative.

One middle ground I used for a while was releasing my projects as a tar file only, not a git repo. Someone else can then make a git repo and maintain the project. Looks like Bellard did the same for some projects.