Abstract question about the "You are here image"

[exponential]

Hey folks,

I have a bit of an interesting question for you all that I'm hoping to gain some insight in.  I'm certain that by now we are all familiar with this image:

https://i.imgur.com/FW34gwu.jpg

My question does not pertain to the highs and lows on that, "chart" but rather, the return to mean line.  Essentially what I'm wondering is whether that return to mean line is influenced by anything, or if the whole image is just a meme.  Is there some formula that effects that line or is it just random?

Thanks for any info and sorry for the random question.