The phone on the other hand is connected to every facet of your life and has a software stack that absolutely contains security flaws waiting to be found and exploited.
Apple has always worked to keep devices secure longer, at least up until now having the best long term support. My favorite part of the Pixel 8 is that Google is attempting to match and exceed what Apple's done so far.
Phone performance and features are definitely not changing fast enough for older devices to no longer be useful, even for affluent audiences. I hope support windows continue to get longer so that folks who must use or choose to use older devices can remain secure.
This is an entirely different subject. The software can be upgraded/updated during the life of the mobile phone. And when it comes to chip makers mistakes, which led to vulns like Spectres, they are likely to affect several generations of chips anyway.