Anticipation

Rowling made a public request that anyone with advance information about the content of the last book should keep it to themselves, in order to avoid spoiling the experience for other readers.^[11] To this end, Bloomsbury invested £10m in an attempt to keep the book's contents secure until the July 21 release date.^[12] However, there was speculation that some shops would break the embargo and distribute copies of the book early, as the penalty imposed for previous installments — that the distributor would not be supplied with any further copies of the series — would no longer be a deterrent.^[13]

OMG. Holy Shyt. That's 10m in POUND. How much they could've spent on the book itself...