I was in Google and helped YT with their search ads (not the pre-roll and "inside the video" and all that stuff everyone hates). Anyhow, I did try looking into their actual "egress" costs and I pity the fool who has to deconstruct that for a court case.

It's immensely complicated, because videos are cached all around the world. Someone in Bangladesh watching YT videos is not always fetching them from the US, you can be sure of that.

So "profit" is definitely an opinion, not a fact. If YT was divorced from Google, it would become a fact.