In the chapter "Hate Bookstore" in Harry Potter and the Chamber of Secrets, why did Harry "try not to be seen by others" in the vault and hurriedly sweep in a few coins?

At that time, the Weasleys were with him. They went to the Weasleys' vault first, and there was only a small pile of money in it. Mrs Weasley searched every corner of the vault. Harry did have a lot of money in his vault, and he was even more embarrassed to let them look at his full vault for a while. He just grabbed a few coins and hurried away.