Which is funny, because as the original comment points out that until after we'd been attacked during WWII, we didn't have a significant standing army. After we were attacked, we started a large buildup, and ended up on the winning side. Every war the US engaged in since then, we've both already had a standing army, and we've LOST. So statistically at least, having a large standing army is more likely to lose us a war.
To be fair, in all of those wars we've lost, there has been strategic ineptitude from the top down in each one. Vietnam was a bad idea, which is why the people of the US protested it so hard. Anything in the middle east has been a clusterf, and even the people choosing to go there knew it was stupid. I'll allow that Korea was somewhat sensible in terms of long-term defense, but even then it could've been handled better. But a standing army hasn't been winning us wars, that's for sure.
It never worked out particularly well for the Army, either. Every war in US history before the establishment of a permanent standing army with NATO is a story of a hasty, disorganized clusterfuck for upwards of a year until a semi-professional organization was painfully established, and it's rarely until year two or three that a really effective force could ever be forged out of the tiny cadre of professionals and the mass influx of untrained volunteers or conscripts.