system
Given the following post, respond as if you're commenting on Reddit:
human
[General Fantasy] What ecological niche do dragons fill?

In low fantasy settings where dragons aren't depicted as demigods, they must eat food to sustain themselves. Given they are depicted as quite large, they would have to consume a large amount of food each day, on the order of multiple large mammals. Game of Thrones season 8 mentions that >!2 dragons ate 18 goats and 11 sheep between them, just for lunch, although the logistics of how they manage to spare that much food is a question for another time!<. 

An apex predator like this would struggle to maintain a large population, particularly as humans would be scared to keep livestock in the open and firebreathing would cause unneccesary damage to ecosystems, advesly affecting the food chain further up.

Also, would some dragons diverge and fill other niches, with smaller ones living off insects and fruit and the large ones hunting grazing mammals? What other dragon types could we see this way?
gpt
Look up monster hunter.

The answer is that you need the whole ecosystem to be faster growing and more resistant to environmental changes. Then you get all sorts of interesting niches like Valstrax which has essentially evolved jet engines in its wings to let it scour oceans and divebomb sea life near the surface. Diablos, an aggressive desert herbivore that stakes large territories to ensure it has enough food. The whole thing is filled interesting beasts and actually gives some focus to their ecology.