That's not how insurance profits work. The profit is the spread between insurer income (premiums) and expense (repair costs).
Right. But if BYD costs more to repair they'll charge higher premiums to cover that cost.
Sortof. There's no guarantee they wouldn't lose customers/revenue if everyone started buying BYDs or NIOs... they could decline to insure those cars at all due to the high repair cost, or not cover all of it, and that affects more than just themselves.