For me its update length. In 2019 I did not have a single Apple product but then I needed a tablet and found that the android side was offering almost no compelling options so I picked up an iPad Air 2 (2014). I was absolutely shocked by the fact it was still getting updates (its getting ipados 15 now) which convinced me to try out the other products so I now own the iphone, watch, ipad pro and airpods. The air 2 went to my mum who still uses it today and it works well.
Homekit may not be as good as Alexa/Google assistant for home automation but it makes an effort to keep all your data local and not in a cloud. A small minority of us really value that.
I understand for regular people though it's really just a status symbol. I spent X on a phone cause I'm doing well in life.