Don't waste your time wondering about cryptography.
Simon Singh has a set of 5 videos on the history of cryptography. Available on amazon prime video.
Codebreakers: Science of Secrecy
https://www.amazon.com/dp/B011NM2ICGIts in 5 parts each about 30 minutes. The last is going public and a great explination of the development of key pair encryption.
His book "The Code Book" also covers the history of cryptography.
Trying to take on key pair encryption, digital signatures and all the internals of bitcoin's block chain will take more time then you have left on this earth when you add in all the other stuff you need to do.
I will say that in my opinion, not even the NSA will be able to crack you private key let along the billions of others being generated. For now it's safe.