Heel Bálor is not a good financial move right now.
It's better for Balor personality wise but from a financial standpoint it is really dumb at the moment. There is so much money to be made on his merchandise because of the Demon branding.
That's true but you make this type of decision with the intent of reaping the rewards down the road. If you bring Balor in with the sole intent on making merch money off his demon gimmick, it'll get old and dry up fast. And if you don't get him over to a high degree, it will limit his earning potential. The sad reality of wrestling is that you generally won't reach that earning potential w/o getting over as a heel. There are exceptions and Finn may end up being one but I don't think he has the tools for it.