It used to be you could find a box of photos or keepsakes that you inherited to look back on how things were or when you were a kid. Now, most of that is stored on phones, and most parents probably don’t think to share or save them in a way to be passed down in the future.
Before digital? Millions. After digital? Possibly trillions? All those photos backed up to the “the cloud” make great training data, though!