You could spend all that money employing contractors producing weapons and weapons research. Or you could spent that money employing contractors producing high speed rail.
Or, more interestingly, you could abandon the "contractor" model which is just a way to siphon public money into the hand of private shareholders, and fund self-organized public services. Self-organized, as in not centralized/authoritarian bureaucracies, but actual field workers coming together and deciding on strategies to do their job (turns out they're usually much better than managers at doing that).
More interestingly, if instead of bombing Afghans you built them a nice high speed rail network along a nice freight network, economically integrating the traditionally independent regions, they may be grateful enough to make the Taliban lose political power.