Sounds like burnout. The reason you can spend days on end coding is because you're excited about the thing you're working on. If you're coding something that you don't find exciting or that is just a pipe dream, you'll have thoughts about your deathbed. That's pretty natural.

Burnout from doing same thing over and over.

Pretty much. Every project I start, it's the same kind of yak-shaving. Database schema, logging, authentication, display of errors, build tools, CI/CD, backend, front-end. Full-time is not even enough for this for one person.

There is a ton of CRUD and mind-numbing tasks you have to churn through to get to the interesting parts, and I have been doing the boring parts for 20 years. The goals barely changed, but how we implement things has. New ways to build, new way to deploy, new languages, new frameworks. Just keeping up with it is a struggle.

I think my next project, I am just going to go Rails. It's my way of giving up :)

clippers to sledge hammers & spikes -- pretty big jump. changing direction to up does get ne off the rail (way) plane.

well, didnt go from cooking meat to oven by not toasting / charing things over & over.

so, software went to crap when the coder's square girl friend stoped emmitting random radiation that sparked idea mutations?

I can identify with that. One tidbit that might interest you, is that most successful startups are not done by kids, but middle aged people.