I haven't decided what my 2020 reading goal is yet, but I'll be aiming to beat whatever I did this year (I'm still reading this month - as of this morning, Goodreads says 25). So maybe 40.
In regards to the 99p boxsets, I suspect there's a method to the madness. Amazon has made it harder to get the attention of new readers using free permabooks, and the number of people that actually read freely obtained books is not helpful (I gave away 13K copies of one book in one year via Amazon and suspect that less than 10% actually read the book, and less than 1% went on to read book 2).
So those authors offering boxsets have probably asked themselves what's a way to attract voracious readers, that are more likely to A ) see the book on Amazon, B ) purchase the book so they've got some "skin in the game" / more likely to read it and C ) entice them to try out an author they don't know yet?
Cheap boxsets is the immediate answer that jumps to my mind, so I suspect it's the same for these authors. They're trying to attract new readers but free downloads hasn't been helpful in their experience.
(This isn't to say we shouldn't give away free books on Amazon - there are still readers out there that do read the free books they download, and review them, it's just [usually] not very effective in the long-run unless the book has hit all the required reader expectations/doesn't suck. I also see no harm in offering a book for free if it hasn't been selling, and using that as a chance to work on the book description/copy to see if that causes download spikes if you're finding ways to get the free book noticed initially.)