Why does the nose become lower after surgery? Reason for reoperation?

Now, looking at the shapes before and after plastic surgery, it seems like the nose shape is different at each hospital, so I'm going to get a consultation, but they say it's too broad...
 I want a half-beoseon, but even the half-beoseon shape that's the same as the rhinoplasty shape is different at every hospital.
 
But even if you put silicone in and cartilage in, will your nose get lower after a few years if it becomes soft? What is the reason for the decline?
 
Is it right that nose surgery can't be done all at once? A second revision surgery is standard, so I'm looking into everything to get a nose surgery, but when I looked at Seongyesa, it seemed like there were a lot of people who were worried about revision nose surgery, so I'm a bit hesitant too.