As always, the Active Army types ignore the Army Reserve and Army National Guard when counting troops. Reserve component soldiers cost about 1/3 of what active forces cost and units can generally be deployed with little more effort than would be required for a comparable active unit.
Your humble servant...
Two problems with your comments on the reserves. First, although your cost & deployment figures are OK for simple organizations like truck companies or quartermaster units, combat arms units need extensive training prior to employment. Single functional combat arms units like ADA or GS artillery are next up on the scale. Reserve Component organizations designed to conduct combined arms combat maneuver warfare ned lots & lots of training to get to a level of equivalence with active forces.
Second, the guys in the guard & reserves are in there for a reason. If they wanted to be full time, they'd be in the Regular Army. They don't mind being called up for the occasional long term deployment or for a national emergency, but back to back to back routine deployments is not what they bargained for