I've been in the industry for >20 years. I've met 2 engineers/programmers that some would call the mythical 10x engineer. These are engineers that you can literally build your entire company on their shoulders because they do everything and they do everything with very few mistakes. The problem with the term is that everyone thinks they are 10x engineers, when they aren't. As I've mentioned, there were only 2 people I've met in 20+ years, so they are basically like unicorns.

One of them was the VP of Engineering for the startup I was working at. He was and continues to be brilliant. He was online almost every hour of the week/day and he was always working. He singlehandedly kept our site up by himself, and when he left, it literally took 5 engineers to replace the work that he did. His leaving left such an impact that the Engineering team almost disintegrated because of how much work we had to take on, and the lack of any truly great engineers to mentor the other engineers.

The other was a friend of mine who was the most productive coder I'd ever met. He would also work as hard as I've ever seen anyone work, and the code that he produced did things I've never seen people do since then. Tragically, he committed suicide 2 months ago, and it's heartbreaking. Probably the intensity to which he coded reflected on the intensity that he pursued every other thing in his life, and when things didn't work out his way, like his marriage, it probably hit him much harder than it would a regular person, who would be rightfully devastated.