You're making the mistake of treating amount spent on healthcare as a proxy for quality of healthcare system. The US spends more per head on healthcare than any other country, but is far down the rankings for health outcomes. This doesn't show that healthcare is irrelevant: it shows that the US healthcare system is so broken that despite spending so much, the outcomes are no better than much poorer countries like Cuba and Mexico. The US is the massive outlier here, and it's no coincidence that the US is also the only rich country without universal healthcare.