Machine code ceased to be scary, or at least mysterious, to me when I opened the rudimentary debugger on a TRS-80. It was really more of a monitor, and it showed the contents of a certain chunk of memory in the top half of the screen. I loaded a program I was working on into it, and began changing instructions in memory, using the assembler output as my guide, and jumping into the program to see what the effects were. After that the little lightbulb went off. Oh, these are just bytes in memory that correspond to CPU instructions, and the CPU just reads them off and executes the instructions.