1. Customer acquisition.
2. Cheap(er) electricity/hardware.
So it's really surprising to me that them making their own chip surprises anyone at all. The electricity thing is already kinda being taken care of by earlier strategic alliances with some other evil people, the chip is a natural next step.
I assume they're doing everything they can to make that happen model-side, but coming at it from the other end makes sense too if they can swing it.