In this particular case the bundle is full of useless and outdated books, the few interesting ones require that you buy the higher tier available.

And given that the purpose of HB is to get money donated to charity, it's not an efficient way of achieving that because they get a very small fraction of what we pay.

Hence why I said you'd better off pirating, evaluate the book value, and if needed buy the book to support the authors.

And if charity is also important because they earn more money.