I'm rather chuffed as mine has just filled shelf four.
Of course the purist might moan that surely lots of these are the same book. But I think it's legitimate to include translations, different formats (e.g. hardback and paperback), new editions with totally different covers and ARCs.
It might seem like self-indulgence, and it probably is. But I think it's something more, which is why I'm respectfully asking you not to disrespect it.
Often, writing a book is a bit of a damp squib of an experience. A new author might think that once the book is published they will see it in all the bookshops, and reviewed in all the important newspapers and such, while in reality it's pretty common that a book comes out and... nothing much happens.
So the physical reality of the boasting shelf, the ability to look occasionally and think 'I did that' to yourself - whether it's one book or groaning shelves - is something of a compensation for not being the next J. K. Rowling or Bill Bryson. And that can't be too bad.