Actually, you don't know if it's not working. One, the incentive to onshore their R&D has ALWAYS been there (look at other industries -- software, auto, GPS etc.). But it's because Two) developing chips isn't easy (or the Chinese, Russian, or Indian would've made much more progress by now). Three, allowing China access to high performance AI chips may help them accelerate their chip design, like Nvidia or AMD use AI to help with theirs. And Four) slowing the Chinese's development in this space gives the US time to plan how to deal with China when they pass the threshold of having sufficiently powerful AI infrastructure for military use.
Let me also add one thing since Nvidia was furious enough to publish their criticism on their corporate blog: Jensen Huang has no reason to care about American competitiveness. Nvidia has too much money, talent, market influence, and partners to be capped by this. He uses that as an excuse to show support for the policy position he prefers (which would benefit his shareholders and him greatly).