A watch is more convenient. I don’t need to take my phone out of my pocket to see the time, I just look at my wrist.

I think you're quite underestimating how many times a person takes their phone out and it's way more than they turn their wrist around to see their watch

I bought a watch about half a year ago just because I was tired of taking out my phone to check the time, so I know what I’m talking about.

Yeah you are talking about yourself and only yourself.

Surely I’m not the only person on the planet who finds it useful, otherwise there would be no cheap watches because nobody would buy them.

Watches, are just jewelry for most people any more. There are few people that can't check their phone for whatever reason that need functional watches, the rest of society mostly uses them for fashion.