Planning to start a Bachelor's degree during my PhD: what to say to my advisor? I am a PhD student on my second year. My advisor is one of the most understanding professors I have ever had the pleasure to work with: he is also one of the, if not the, most important researchers in his subfield, which is a really "academic" subfield, meaning everyone who studies this subject ends up in Academia, or with a really unrelated, low-paying job.

Now, I am really unhappy with my PhD: my research is, in my eyes, very weak (I know, I know, impostors' syndrome and so on, I am in fact looking for psychiatric counseling but, one must be realistic: from all PhD students, statistically, some are bound to underperform) and, overall, I am just not happy with what I do... Somewhere along the road I lost the little interest I might have had for research.

The thing is, I used to enjoy research, at least a little, and Academia offers very comfortable careers in my country, and other countries as well: I don't want to leave, study a new subject and find that, not only I am not suitable anymore for Academia, but also I hate whatever I started studying; and I hope that, maybe, with the right counseling, I might again enjoy what I do. Furthermore, I have a scholarship, and if I left with my PhD unfinished I would be heavily financially penalized...

So, the idea I had was to start a Bachelor's degree in a field that has better prospects outside of Academia, all while continuing my PhD: I will underperform even more in my research, but that is a price I think I am willing to pay. The problem is, how do I break the news to my advisor? 

As I said, he is a very understanding person, but it will be clear to him that my intention is to, very possibly, leave Academia, since our field is so "academic" and the one I will start this new degree on is not. He will also be very unsatisfied with the obvious new drop in performance and, in my opinion, there are no good reasons to maintain under his supervision a PhD student, in a very academic field, that is not willing to stay on the field.

So, how can I tell my advisor of my intentions? Should I not (which, from a legal standpoint, seems possible, but I would feel extremely guilty)? What kind of arguments should I present to him, in order for him to keep me under his supervision? Would it be more fitting to just drop the PhD instead? I know this question could, perhaps, fit better in the Interpersonal Skills Stack, but the intrinsic topic is so very dependent on academic matters that I think it is a better fit here.
This is probably more of an opinion answer, but I would say you should say to your advisor either:


  I'm leaving my PhD because _________ and I am going to instead get a bachelor's degree in _______.


or


  I am not feeling good about my research progress and not enjoying research to the point that I am considering leaving the program - can you help?


To be blunt, your plan to do both at once sounds like a horrible blunder. If you are struggling in your PhD now, adding an additional set of responsibilities is not going to make that problem go away. I can't imagine your advisor giving you any different advice than I have.

Further, if you choose to not tell your advisor, I think this would be akin to what is described negatively as "ghosting" in the context of a personal relationship, which is considered to be incredibly rude towards anyone you have an established contact with. Slowly letting your performance decline while you stop paying attention to your PhD and start working on other things is just going to make everyone miserable, and probably destroy any chance you have of getting a good recommendation from your advisor in your future endeavors.

You suggested you've been looking for counseling, and indeed, if your mental health is suffering, that would be a good idea, much better than your plan to take on additional responsibilities.