Most people who stop publishing do not stop because they ran out of things to say. They stop because the process around the writing became harder than the writing itself. Nobody plans for this in advance, which is why it quietly ends so many projects that started with real momentum.
The gap between an idea and a finished piece
Having an idea feels productive. Turning it into something publishable rarely feels the same way, because it involves the less exciting middle stretch — structuring, cutting, checking, formatting.

A writing habit rarely dies in one dramatic moment. It dies in the quiet week nobody noticed was the first of many.
Writers who publish consistently over years have usually built some system for that middle stretch, even an informal one, so it does not have to be reinvented from scratch every time.