https://www.shs-conferences.org/articles/shsconf/pdf/2024/27...
Just 2018 to 2022, BYD received $5.9B. And that doesn't include all the indirect subsidies that went to suppliers like the battery manufacturers.
It's a part of Chinese government strategy of "build it and they will come". Massively subsidize select industries, dominate the market.
Which is why the EU has put high tariff's on the cars.