A couple of little tidbits: the magnetic core memory was a "destructive read" cycle, meaning that the data had to be re-written to the core every time it was read. (The read mechanism was that you'd try to drive the data to a specific value, and if it already was that value, there'd be less impact on the "sense" line than if it was at the opposite value.). The re-write was usually taken care of by the hardware.

After 10 to 15 years of continuous use, the copper wires would crystalize and the array would fail. (I'm old enough to have used computers with actual core memory.)

Core memory has the advantage of being non-volatile, meaning that if you remove power it does NOT automatically "forget". (True, the uSD card also has that property, though I'd be inclined to bet on core for "remembering longer", though it's very doubtful that anyone reading this comment within a few decades of my posting it will be around to settle the question.)

The individual cells in the uSD will eventually wear out if written often enough, but again, it's unlikely that any of us will see that (unless we do something like write an "update" every 10 mS).