Answer is simple.
Why isn't U.S. better at Field hockey, Badminton, Cricket, Ping pong etc.?
Ideally a capitalistic system is supposed to produce the best or close to the best in each category to stay competitive then what gives?
Capitalism produces the "best" in categories where there is a high demand for a product. In the U.S., the demand is for high-scoring, high-production-value entertainment. This is closely entwined with "culture".
This is why the U.S. leads in sports that are tailored for television and massive stadium revenue. Sports that are more nuanced, low-scoring, or lack a domestic TV or the US cultural zeigeist simply cannot compete for the attention span of the American consumer, and by extension, the capital that follows that attention.
> the demand is for high-scoring, high-production-value entertainment.
What part of American football or baseball is high-scoring or high-production-value or entertaining?
Is modern baseball "high-production-value entertainment"?
For basketball and American football, those sports weren't exactly blockbusters either. The rules and strategies of those games have been carefully tailored over the years to cater to action and scoring, something that was never going happen to the rules (or laws) of soccer.