Also why anti-dumping laws exist
(Legitimately asking: I don't know the answer ... but based on most US business law my strong suspicion is ... no, they don't.)
By that account China would be bankrupt by now because subsidizing a "buttload" for "decades" does cost a lot of money.
I think the reality is much more subtle - they force their way into a new market if needed and then stop and let the market forces do their thing.
America can't do that because the government takes bribes from banks and believes in Friedmanite ideology where state investment is evil. It's a great opportunity for Europe to copy China and become independent.