Wait, why are you mixing the two? You can have the software be under an open source license, yet still not be a monk that has taken a vow of poverty, it's not black and white.
AFAIK (as a long-term Obsidian daily user) Obsidian makes their money on various things attached to the editor/viewer itself, but don't actually charge for the editor/viewer. Even if they did, they could still slap a FOSS license on it, and continue charging for the parts they charge for today.
I'm guessing it's something else they're worried about though, rather than those things.
I agree with your very last part though, but I don't agree you cannot make it open source at the same time.
AFAIK (as a long-term Obsidian daily user) Obsidian makes their money on various things attached to the editor/viewer itself, but don't actually charge for the editor/viewer. Even if they did, they could still slap a FOSS license on it, and continue charging for the parts they charge for today.
I'm guessing it's something else they're worried about though, rather than those things.
I agree with your very last part though, but I don't agree you cannot make it open source at the same time.