> Computers are just a machine like a 3D printer. You're "physically" moving bytes of data around (that's where most of the heat comes from), doing operations on them, etc. Nowadays you generally can't get them to destroy themselves but in the earlier history you absolutely could tell the machines to tear themselves apart in the same way you can tell a 3D printer to tear itself apart.

This is wrong. It's not what 'unsafe' means for C or C++. You could have 100% safe hardware for your code to run on, and your code could very well still be unsafe. The phrase you're looking for is Undefined Behavior.