About 50% of all R&D worldwide happens in the US. The US's global share has shrunk a bit, but only because China and India have grown rapidly, not because Europe has ramped up (it hasn't).
Some new drugs are developed in European countries, or by European pharmaceutical companies - that's true. But European pharmaceutical companies all make a disproportionate amount of their revenue off of sales in the US market. So Europeans quite literally benefit the most from the fact that Americans pay more for the same drugs.
Yes, I agree that it's a foolish choice for the US to subsidize foreign countries' healthcare in this manner. Regardless of this decision that we both agree is foolish, it means that it's misleading to compare cost-effectiveness between the US and other countries directly.
Can you elaborate? Genuinely interested in the details.