BYD also owns the entire supply chain, from lithium mines to battery manufacturing to car assembly to sales. Nobody else can do that right now.
And China has the overwhelming advantage in lithium supply to the rest of the world.
IIRC it’s not R&D that is the main cost of EVs these days, but the cost of the batteries themselves is still absurdly high. It’s down to $139/kWh as of Nov 2023, but keep that in perspective of an EV: a 72 kWh battery is $10k in raw material costs alone. I think I remember seeing a quote that affordable EVs (unsubsidized) can’t become a realistic goal until lithium prices break the $100 threshold.