How to stop hopping the learning chain and actually begin somewhere? Here is what I feel whenever I find something interesting and feel like pursuing it : 


Oh so I like X (Computer Graphics), let me read up papers/books about it.
Ok let me begin with reading up Y (OpenGL)
But Y needs W (Linear Algebra)
Well reading up Z (Probability) first makes more sense.
Umm, you shouldn't jump to Z without learning U (Permutation/Combination).
And how come I forget about reading V (Number theory)
And what not..


I always end up searching and reading up "Best books to begin A/B/C/D.." instead of actually making myself begin somewhere. This consumes all my energy and I never really start.

Q. Have others faced this ? Q. How do you handle this and actually begin somewhere ?

Any help would be really appreciated.

Background : I am a working professional, with Masters in Computer Science (fascinated with Computer Graphics etc). Its been two years since my masters but I still kind of miss academia, my thesis work and other interesting stuff I did there. My current work is also pretty interesting and partially overlaps with my interest areas. However, other than work, I would really want to continue doing things related to my masters side by side (and MAY BE take up a Phd somewhere down the line). But the never ending feeling of not knowing anything takes over.

Its not that I am being forced to study any of this. Its purely for my personal interests that I want to pursue it.



Update 1 :

Thank you so much everyone for such overwhelming response. I really like several answers and points raised but haven't marked any yet because I am in the process of trying some and would update if something actually works for me. Meanwhile, I also found this talk really helpful : 

https://www.ted.com/talks/tim_urban_inside_the_mind_of_a_master_procrastinator
Dan's answer is very good, and I want to add one more point:

Accept that on the first pass you will not be able to fully understand the topic. Appreciate that there are decades and sometimes centuries (for the math, at least) of research supporting the topic you're learning. Thinking you can "get to the bottom" of it in a few months, let alone a week or two, is not realistic. Choose a topic and try to understand that as much as possible. Keep notes on other interesting topics along the way, but don't get distracted by them; just accept them as assumptions as this point and move on. You can get back to them later.