Why do people want to learn 3D printing and how does “knowing 3D printing” compare to “knowing how to be a software engineer a few years ago”?

Taking this question literally, as I tend to do, I think knowing 3D printing—in the sense of designing something on a program and using a 3D printer to bring it to physical being—isn’t much different than knowing regular 2D printing a couple decades ago. I might also compare it to digital photography. I feel that the skill is in understanding how to use the program or to even build the printer and not how to plug a file into a machine.