As another data point - I’ve never looked at YouTube for database content, but every single DBA I’ve encountered in the corporate world pronounces SQL as ‘sequel’.
Anecdotal, but fair, since I can say the opposite. I've largely heard it said as S Q L, ro the point when someone verbally calls it "sequel" it takes me an extra moment to remember what they are referring to. I rationalize it thus; we don't make words from our other acronyms that aren't already pronouncable words to some degree. Exploring that, we don't say "fibby" when we mean FBI or "see ya" when we mean CIA (maybe we should, though?). DARPA, on the other hand, is pronouncable on its own, so we'll say the word instead of D A R P A. Another one is HIPAA, which is interesting, since its pronouncable, but people often get the acronym wrong as HIPPA when writing/typing it (FAFSA being another good example) although that is more US-centric.
Anyway, our treatment of saying the word instead of saying the letters of the acronym is interesting to think about, I guess. I reckon there's a lot of cultural and linguistic influence there. Perhaps someone smarter than me can unpack it.
It is interesting. I always thought it began as ’sequel’ and was then abbreviated, but I wasn’t around when it started back in the 1960’s or whenever that was… might go google it haha