Data Science
I believe that machine learning and AI will change the world. (I include the word "AI" because I believe non-ML AI will also be useful.) Although I took a few comp sci and statistics courses in school, I'm mostly a self-taught data scientist.
Check out my curated list of data science/machine learning resources. Also, I've prioritized the online courses that I've taken / will take.
In 2020, I gave a talk on document embeddings and their use in recommendation systems.
It's funny that, after taking "Introduction to AI" at Stanford in 2001, my conclusion was that it was a dead-end field. Basically, "AI doessn't work." Boy, was I wrong. I regret I didn't get back into machine learning until 2015. Better late than never. (Got into analytics in 2011, that was a nice stepping stone.)