I'm not sure how much I'd obsess over Amazon Fantasy Gaming rankings. Gaslands Refueled is up at #15 and Realms of Runeterra pre-sell is up at #2.
As far as all the others books - the Bestiary, Lost Omens Guide, etc... they're all behind the Fallout Cookbook lauched over a year ago, so we're likely talking it's lucky if they are selling copies in the teens per day.
I suspect Paizo is selling a few dozen CRBs a day in order to stay in the Top 100 and they probably net $25 for each of those sold. All in, they're probably netting $1000 a day selling through Amazon for all products, which is a respectable $30K/month. They are probably getting $ via BN + all the FLGS added together.
Paizo's an interesting company that will likely be around for decades. I think you first need to think about it at it's core like a virtual FLGS selling non-Pathfinder product. You can buy minis, board games, comics, Warhammer, CCGs, checkers, etc from them. Their "core principals" (Lisa, Vic, Jeff) and their warehouse and support staff could probably survive at break-even without them ever printing another Pathfinder or Starfinder book.
Then you just need to think about Pathfinder/Starfinder being break-even and self-sustaining. When you get down to it, they can survive off just Bulmahn and Jacobs cranking out rules and setting books a few times a year. Their organized play staff work inexpensively and I most adventures are volunteers writing them. At $5 a pop and all digital in-house fulfillment, they can sell two scenarios a month at 1000 downloads and PFS and SFS are each bringing in $10,000/month each to cover those developers. All-in, both Pathfinder and Starfinder could net $1M a year and have room for a few supporting staff and survive off just 1-2 rulebooks and a few setting books a year and only a few thousand AP subscribers/purchasers.
Remember they've shed a ton of veteran staff and cost since 1E - Reynolds, Brock, Sutter, Schneider, Frasier, Price, Radney-MacFarland...