How does that compare to each other little area of spending? If you have 100+ categories of spending to look at, 10% of the market in a single spending area can be some pretty low hanging fruit.
Spending in physician/nurse compensation is higher than spending in drugs. If reducing the price of drugs to European levels would result in big savings to the system, imagine the effect if the compensation of healthcare professionals was reduced to European levels.
Let's say we reduced US drug prices down to EU levels. Branded drug sales are about 80% of all US drug sales. Reduce that by 25% and we've reduced US healthcare spending by 2%. Decent, but certainly not enough to solve our healthcare spending problem.