1. It still took nearly 7 years to after JFK's speech in the 60s.

2. The institutional knowledge of working directly on the Apollo program has largely been lost in the US, and certainly isn't present in China.

Those are the unimportant pieces. The real reason is:

3. The US was actively at war with Russia. While it was a cold war (except for the proxy wars), the Apollo program had a wartime budget (spent nearly half a trillion in today's dollars), and a wartime risk tolerance (Neil Armstrong thought they had a 10% chance of not making it back).