We spend way, way more on healthcare than defense. If you diverted every penny from defense into healthcare, you'd see one of three outcomes:

1. The optimistic one: modest but meaningful improvements take hold in healthcare outcomes; nothing revolutionary, but good enough evidence that dumping more money into healthcare without systemic changes can still improve things.
2. The pessimistic one: corruption and inefficiency in distributing new influxes of funding into healthcare results in a situation where everything is even more corrupt and less efficient, and the extra money results (at least indirectly) in worsened outcomes and accessibility while accelerating the deterioration as those windfall profits are internalized.
3. The mixed one: some small gains are offset by some small screw ups and the net impact of the monetary infusion is ambiguous, with some dimensions of healthcare getting some measurable improvements and others actually getting worse.

In all three cases, the consequences would likely be irrelevant fairly quickly because the geopolitical vacuum left by the US military vanishing would destabilize global economies (even more) and likely spark wars we no longer had any defense against.

Reducing the US role as world police and improving US healthcare need to be tackled as separate problems with different timelines.

• For defense, we need phased handoff of accountabilities to trusted allies who step up to the plate; Russia is a really clear reminder of why the lifetimes of comparative peace (and outsourced violence) that most readers from Western countries enjoy is not a given — and with continuing pressure building from developing world population growth and climate change, the backdrop of instability isn't realistically going to improve all that much over time. If the US is going to pull back its defense spending, it needs to do it slowly and methodically. In reality, it may be better to just spend it more intelligently, which is something that e.g. semi-autonomous warfare initiatives like the drones discussed in this article could actually do.

• For healthcare, we really need to fix the money-leaking system before we just dump more money into it. We already pay way, way more than anyone else in the world for "good but not always the best, highly inaccessible care" and we should expect vastly diminishing returns if we just throw extra funding at it. It's a lot more complicated than just wholesale switching to a single-payer system, but most of the "exponential profit machines" do need to be removed from the equation; without checks, free market is going to naturally converge towards highest cost for least-quality acceptable product, and even if that anti-capitalist sentiment is exaggerated and oversimplified there's still clearly some hard truth to it in what we see happening.

If we find a way to cross the streams and divert some incrementally and intelligently pulled back military spending into a reformed healthcare system that actually makes good use of that money? Then fantastic. But this is far, far more layered than "military bad, healthcare good, give military money to healthcare, good!" ... Which is unfortunately a prevailing sentiment.