They also had several pools/ jacuzzi. It was basically a small resort. Buying a couple of month supply when you are on an island and everything has to be brought in by boat, not really surprising at all, especially not when you put in the context of the rest of the buying they were doing. Even basic pool contractors buy at those levels.

Also, they had an entire ocean to dump bodies into and an entire island under their control to bury them. Acid digestion seems superfluous.