I've met some people with physics and accounting degrees who took boot camps and had success, but the people I've seen succeed were already problem solvers and math-aware. They just needed to know the language and routines.
On the other hand, I dropped out of school and have been programming for a majority of my life. I was never accused of being incompetent or underperforming, but there was a point in my career where I was not going to progress without deeper math skills. That said, it only takes a couple years to learn.
Books. A lot of people gave me books, many college-level books are free on the internet in PDF form. I also had to read back through algebra and calculus to pick up on some concepts I had forgotten. Earlier in my search I used Udemy and Khan Academy. There's good courses on both but they really only get you so far, imo.
I'd be interested to hear more about this, as someone potentially in a similar position. What kinds of problems did you come up against where you felt your math skills were a limiting factor? What branches of math did you focus on learning?
Well, I've worked in cryptography orchestration (not actual cryptography, but I needed to understand how it worked from a basic POV) and in reliability engineering which is very stats heavy. Both of those became limited as I got more senior. For instance, a lot of problems can be identified by bucketing them in distributions - I didn't even really know or understand the math for representing a distribution. The long tail of where I actually used that was in a program that I used to create mock data for a set of devices my company was working on that simulated real household resource usage. These same math skills also became problematic as I started to need to learn/understand better applications of algorithms and data structures. There's a lot of assumptions baked in to things like asymptotics that you won't get without a background in math as well. You can certainly memorize certain things, but that has diminishing returns imo. I think I answered the last part above, but I refresh algebra and calculus. I read a stats book, took a Discreet course on Udemy, and read a lot on DS&A. I think that covers it. Took me about 3-4 years to chew through most of what I learned in my spare time.
On the other hand, I dropped out of school and have been programming for a majority of my life. I was never accused of being incompetent or underperforming, but there was a point in my career where I was not going to progress without deeper math skills. That said, it only takes a couple years to learn.