Over the years I have had that happen to me a few times. At times one has to wonder if it’s intentional, e.g. vindictive. Otherwise it’s grossly negligent or purposely careless.

You would think that adults would understand basic physics. Unless properly secured a loose object will move around until it meets an irresistible force, namely the sides of a box.

But sometimes, even a carefully packed model gets loose. I have seen that happen.

Have you written to the seller? You should. Ask for your money back or file a complaint with Ebay.