> generally successful democratic socialist countries in Europe where standard of living is better by many measures than in the US?

Most of those countries have had 80 straight years of paying almost 0 for their defense. Who was paying for their defense?

If we had some other country guaranteeing our security so we could pay almost nothing for it, we could indeed double our spending on healthcare!

And no, that defense spending isn't a waste of money. We don't live in a safe, secure world; much of the world merely appeared safe and secure for a few decades because it was too hard to challenge a dominant US military. Unfortunately, new technologies of asymmetry, such as cheap drone weapons, are reworking that math.