Moving parts wear out. I had a 2006 Toyota that I purchased new in 06. I gave the thing away about 9 months ago. During the time I owned it, I had to replace Serpentine, a battery, and an alternator, all withing 750,000 miles.
Speaking of Toyota and Miles, I heard about then saw/read the Article of a Toyota Tundra with 1,000,000 Miles. Yes 1 Million Miles.
It was a Parts Delivery Vehicle that ran parts all over the country from Dealership to Dealership. I don't remember all the details, but do remember at 1 Million Miles Toyota called it back to the Factory to tear it down for Worn Parts Inspection.
They found very very little wear and most of the Engine Parts were still within Factory Specks for NEW PARTS.
Here is that Article:https://www.motortrend.com/news/million-mile-tundra-the-tear-down/
It was pretty amazing to see just how far things have come from the 60'-70's where we talk of the days with the "good engines that had power" and call them the Muscle Car Days. Those engines were shot by 50-80,000 miles IF there was anything left of the body and it hadn't rusted out.
My SS Nova came from the Factory with a 2-barrel carb pushing 105 hp. Today a 4-cylinder from the Factory can be pushing 300 hp. Crazy .