This is an interesting aspect. However, I do believe that devs indeed will suffer bad luck more than the average "person on the street" - it is statistically well known for both IT personnel as well as self employed people to have more health issues than comparative (similar age, wage, ...) people in other fields or with other employment status (well, I guess it beats being unemployed) due to more psychological stress.
This is one of the reasons why I am not a great enthusiast of "one developer games". Project shouldn't be stopped because someone gets sick which automatically happens when project has only one person (and I'm not writing here about HM).
I very rarely comment on development process here on the forum, because you can be easily accused of ill will but I am making exception here because I care about HM.
I think the main problem of Headmaster project is that Altos tries bite more than he can chew ie. he constantly expands scope of the game and focuses too much on small details. If you are alone or you have small team, you have to make some big compromises. Finishing Headmaster with basic assumption of making punishment system for Liz, Alice, Twins, Faye (each of them probably requires 2 updates, 1 update per 3 levels), finishing Debbie's, Cassandra's and Amy's story, finishing main plot probably in chapter 3 is a lot of work. In my opinion, still too much for several people. Solution to this problem isn't adding new side attractions like Maxime fundraiser but focusing on the goal, hire new people if you can, and seeking shortcuts which leads to point two:
There is too much focus on the details. Spending lot of time on smoother animations, red butt effect, rendering each scene when it can be replaced by sprites talking to MC in FPP mode, making countless combinations of animations in Punishment System. Yes, all these things are cool but personally I prefer simplier and completed game in 3-4 years than all of above.
I think that Altos needs 20+ (including writers) people if he wants to complete Headmaster according to his vision which is unrealistic at this level of funding. Nevertheless, I wish best of luck to him.
To be honest, the above are the main problems of many games here.