Were you born with the knowledge that a video takes more space than a photo that takes more space than a text?
Or is it rather that you consider yourself one of the few people smart enough to memorise it? I find that very condescending.
I don't believe that one needs 3 postdocs to understand it. In fact, I do happen to have explained it quite a few times, and I don't remember anyone not understanding it.
It's quite clear what you never had to explain why 'only looking at a pictures/photos on the Internet' wasted the mobile traffic.