BYD is eating everyone's lunch at the bottom not just Tesla.
Tesla could have prospered by sticking to the mid range but their build quality is appalling even for a lower mid car.
Couple that with some truly dumb design ideas from Elon (no lidar, no physical buttons, indicators as buttons, stupidly high repair bills due to design choices) and some even more stupid personal behaviors from him and he has just cut the legs out of his market.
EV buyers who are spending more money care about this kind of thing, budget buyers it is mostly about price.