Our understanding of gravity explains a phenomenon clearly and directly. It is one idea, easy to understand, explains so many phenomena, can account for a large amount of data, and answers many questions. In other words, we can say that gravity is elegant.
In contrast, each of the different concepts in the flat Earth model requires a separate explanation and often in conflict with each other. We can say it is ugly. It is why flat-Earthers cannot accept that a single idea of gravity can explain so many phenomena.
In the beginning, Newton brought up the idea that everyday things falling down and the motion of planets are actually caused by the same phenomenon that he called gravity. In time, we also know gravity can also explain so many other things and led us to understand things we previously don’t know.
On the other hand, flat-Earthers are so used to inventing new “explanations” for every different phenomenon, which often in conflict with each other. They think that gravity can explain so many things is ridiculous and impossible, and that scientists are just making that up. Flat-Earthers often mention the many things that are explained by gravity to ridicule our position. In reality, gravity can, in fact, explain these things consistently. There is nothing ridiculous about that.