I knew in a vague sense, but it hadn't been brought home to me so acutely. It is something or at least to me at the time, known but not really attended to; but is now.
I always have backups on externals and really only used it for basic graphics more than photos, but yes, I was lazy and shortsighted.

I had that happen once in one of my graphics classes in 2000 when an instructor emailed me about some of my work being modified and resubmitted. She asked if that was my original work, which it was. Later I received an email from admin. apologizing and saying the student had copied others too and been expelled. They instituted new procedures and life went on.
However, I always wondered, why pay for something and then cheat? What did the person receive out of it other than loss of a lot of money and expulsion? What was the point?

@Angelface Watermarks sound like a good idea!

@RavenCT I had them. They can be tampered with electronically even more so than back in 2000.

I still remember reading about the woman who came upon a picture of her son in a private adoption advert. His photo had been lifted from her Facebook page; as were the images of other children. This event was years ago, but I imagine it was quite a shock.

@Angelface Yes this is the thing that worries me the most. That's just horrifying.

And yes I figured an easy watermark would not be easily removed. (Sigh).