“Just let us know when it breaks.”
Complete failure is unlikely (but would perhaps be the worst disaster in recorded history, if it did happen).
In the meantime, the flooding that has been happening, is a huge disaster by normal standards. It impacts global agricultural demand and prices, and threatens the supply chain for lots of critical supplies, like PPE and pharmaceuticals.
So there is interest just in the flooding itself.
But for preppers, the worst case scenario is of interest, because the effects of a sudden complete failure of the Three Gorges Dam would be Global.
Geostrategically, the effects on China would be akin to a medium nuclear weapons exchange.
The Chernobyl disaster was a prelude to the collapse of hard core communist rule in the former USSR. That event I think shook the Soviets more than we realized at the time. Not sure this flooding would be similar but there is the idea that totalitarian regimes have everything under their control and obvious disasters call into question the legitimacy of their rule.