Which topics are hard to self-study?

In chemistry, the part with the chemicals can be kind of challenging. The more toxic, the less you would probably want to do it on your own. Many labs require more than one person on duty as a safety consideration. I would usually suggest "don't try this at home" :)

Throw in trying to make progess with electronic chemical laboratory instrumentation and there's an even bigger hurdle.

And that's without even necessarily getting into actual electro-chemistry.

Regardless, I did it anyway in what became my private practice, but definitely not at home nor in my spare time.

As far as the CS aspect, I just wrote the code myself as I went along, they didn't have commercial software when I got started, and when it came out it was not exactly what I needed plus too costly for just one person anyway.

Anything that involves another human. Massage, psychiatry, customer service, anatomy, doctoring, etc...

Anything I'm not currently hyper focused on, as someone with ADHD.

Ruling & upper class wealth management and politicking, as a peasant.

This 17 year old had a try at nuclear.

https://en.m.wikipedia.org/wiki/David_Hahn

Easiest topic to self study = any philosophy. Most difficult thing to self study = how to use expensive and complex lab equipment.

* UX

* Practical project management and team management

* Anatomy