Without debating around the edges (because yes,in practice there is almost always someone winning and someone losing), a market model only works if profit is a function of a sufficiently competitive market, and not other structural, cultural, or political factors and barriers working against that outcome. And your implied equivalency largely ignores those factors present in the US.
Indeed, the theory that a competitive market can actually deliver socially efficient outcomes could almost be said to be predicated on the idea that yes, you can push down profits substantially without quality deteriorating, because market outcomes are not driven just by profit making motives on the producers' side, but also competitive and structural considerations that determine the nature of competition and consumer demand, competition, and substitutions in that market.
So if the US healthcare system generally delivers worse outcomes and costs more (and that's something I generally take to be true), I think it would be a mistake to come at it from a simplistic point of view of an efficient market already operating and saying that any cut would worsen outcomes, because your opponents position is not predicated on the US health care system being a competitive market. Indeed, we need to take into consideration all the other structural qualities driving healthcare delivery and outcomes in the US market. And compared to most other countries, these differences are usually quite substantial: everything from your political process, to where and how health care is typically purchased and received, how your insurance market works, to your social security and labour laws.
There is nothing, in even basic neoclassical economic theory, that implies a market is optimal, in either supply quantity or quality, by maximising producer profits or surplus.