The fear was much more real back then. I too grew up with a family computer, but I was the only one being able to both break it and then fix it afterwards... Fortunately, there was nothing that couldn't be fixed by reinstalling the OS, and I quickly picked up on the advice to have separate "System" and "Data" partitions, so you don't lose anything important if you need to wipe the OS.
Reading this makes me realize how incredibly lucky I was to grow up in the eight bit days. When we got our first family computer, a ZX Spectrum, one of the first things I learned is that it was 100% impossible to break the thing just by pressing keys on the keyboard. Just unplug, restart, and the whole tiny system is loaded from ROM. That gave me the freedom to explore fearlessly what the system could do, and what I could do to it.
Edit: I'm sure by now somebody has found a way to thrash the system so hard that it somehow causes irreversible hardware damage just by running software; but I guess that would have to be the result of considerable, purposeful effort from somebody who knew exactly what they were doing.
