Should I mention in my PhD application that I'm quitting my job in a month to spend time learning about the subject? I'm working as a software developer right now and am applying for PhD programmes in robotics and environmental conservation. I've put in my notice at work recently and should finish working there mid-February, about a month after the PhD application deadlines. I am quitting for a number of reasons, one of them including wanting to focus on learning how can I help the environment with my tech skills. One of the ways I can is to do research in a relevant field - hence the PhD.

I was wondering if I should mention my quitting in my PhD application. On one hand it demonstrates dedication to my interests. On the other hand, leaving your job without anything else lined up is an... unorthodox move in the professional world and I can see how it could be taken as a sign of volatility. What does stackexchange think?
From the admissions perspective, it shows dedication but also chutzpah in a bad way. 

Many competitive programs have an admissions rate between 5-20%. Even if you are a strong candidate, it is not guaranteed that you will get in anywhere this year. This is why you have to apply to multiple programs as well as have a backup plan if you don't get in anywhere. Staying in a job (you might hate) would be such a backup plan and would show that you are someone who has Plan Bs.

If I read your application, I would have a nagging feeling at the back of my mind that you are rather sure of yourself and/or desperate and/or headstrong. None of these are good qualities for doctoral programs. 

There's also a slight feeling of being extorted - as in, if you don't admit me, I'm screwed. But that's not our problem, you put yourself in that situation, yet it still leaves an unsettling feeling.

Neither of these are enough to tank your application but it could sway someone on the cusp of denial/admission towards denial.

tl;dr: A much stronger application would be one that says, "if I am admitted, I plan on quitting my industry job in May and spending the summer ahead of matriculation preparing for graduate studies by doing xyz."