hmm. My first (and only) iPhone has been the 5s. I like some others, but not enough to buy one.
New iPhones hold no significance for me to get a new one just because it is new.
I got the 5s only because I was ready to move from my old LG Touch 😀
So, I have pretty much skipped all others.
Likely I will buy another. I will probably be ready to replace the 5s in another couple of years, maybe 3.
I tend to replace phones after 5 and 6 years.
I don't think I can link that (somehow) to Tim Cook, as he is not my 'leader'.
I guess you need to re-evaluate your supposed need to replace your devices every time a new one is released.
That's not something that has ever interested me.