One of the most formative events for me as a programmer was playing with the gameshark on ps1. It had a debugger where you could press a button on the device and it would halt the system. Then you could search through the memory and alter values. Realizing that everything you saw and did, everything about the state of the entire game world was just numbers in memory was mind blowing. It instantly broke the illusion, but what it was replaced with was even more magical.
I realized that I could do things like set the health bar, or number of lives to a fixed value. I could change the height of the character and "fly" around. I could do anything, as long as I could figure out how it was represented in ram.
It was a pretty big deal to 10-year old me. A few days later I was using a computer and it dawned on me that the same thing applied to the computer I was using at school.