Flood fill vs. the magic circle

I remember when I first heard of the concept of "cyber-attacks". I thought "but it's all just pixels on a screen, you can't actually hurt anyone that way unless people give the computer power." As a budding software developer I couldn't fathom the idea that people would trust software enough to automate critical infrastructure, or automate weapons, or give a computer the ability to spend their money, or keep track of where they go and who they talk to. And if they don't do that... then everything is cool, right? Yeah, I was young and foolish.