This is a perfect example of synthetic versus real world testing. Of course repeatedly folding the display in a controlled environment worked fine - this flexible OLED tech is the reason this phone took almost a decade to engineer. But this display doesn't exist in a vacuum; the real world is full of lint, sand, and dust. That's why phones have shifted towards the "sealed slab" design - the reduction of moving parts and points of ingress have worked wonders for their durability.
The Galaxy Fold feels like an over-engineered solution to a problem that Samsung created themselves. By placing the flexible panel on the inside of the Fold, they not only had to add extra cameras and another display to make it useful when closed, but also created massive points of ingress. And for what gain? The outer display looks incredibly outdated, and the need for all these extra components is likely why the Fold is so outlandishly expensive.