After taking a break from software side-projects to work on more physical things (woodworking, metal-working, welding). I have to agree that software is one of the most complex things we work on. Even something quite complicated that's evolved over decades, like a car, is largely comprehensible to a single person without an enormous amount of effort (i.e. many people understand how every single subsystem of a car works), while understanding everything in say linux or postgres takes a much higher level of effort (it can be done too, but there is a lot more complexity to keep track of).