But I think the premise: "the World’s Biggest Military Keeps Losing Wars", is wrong.
1. Conventional forces have trouble wining asymmetrical conflicts unless they are allowed to wage total war (which is usually precluded by modern political/moral concerns). Nothing new here- the Romans had experience with this.
1.A Note the single "win" on the list of post-Korea conflicts was the first Gulf War, a conventional conflict.
1.B It is arguable that the U.S. is actually better than most other conventional militaries at asymmetrical warfare: http://www.warriorlodge.com/blogs/news/16298760-a-french-sol..., however that may just be a product of being better at conventional warfare improving overall fitness.
2. "Winning" define this? Winning means very different things in total war vs. occupation/garrison/nation building actions. While its fair to say the U.S. lost Vietnam, I think its fair to say the U.S. won in Iraq and Afghanistan as they are now governed by friendly democracies... Military action is just a way of attempting to physically impose political will- If a nation's military helps the leaders reach their goals, it won.