aside from the huge domestic market (or potential in the future), china has built incredibly efficient infrastructure for manufacturing prototyping/production.

but it's also thanks to protectionism, and their strictly controlled (not freely traded) cheap currency.

if china had to play by the same rules as japan or germany it would not be quite as successful. but the west walked into this trap, hoping their win-win proposal would be satisfactory for all. now the west is too dependent on chinese production to enforce equal standing.

of course the US has its own unfair advantages, e.g. the global reserve currency and the massive post-WWII headstart.