Im currently trying to crack it. What I've realised so far is that once you get past the scary mathematic notation, its really quite simple under the hood. Maybe that wont be the case as I learn more, but linear regression and gradient descent is really very simple and easy to grok.
So far I've been cobblibg together a learning regimen by combing Coursera, Khan Academy, and a book called "Machine Learning for Programmers". Individually they all eventually brush over some key concepts that make it dofficult to get an intuition for what's happening. But when combined they fill in the gaps. Also, this repo has been like the rosetta stone for someone who doesn't have a single maths qualification, not even a GCSE.