Not to overthink this issue so much:Consider the alternative - they couldn't leave their fragile client government that would likely lose to the Taliban. Which is exactly what happened when they left, although much quicker than anyone wished to believe.
Also consider how there were significant troop withdrawals in the last years, so there were less fighting and less soldiers already. If the conflict was ruled by shady weapon manufacturers, they would have wanted a full scale war where expensive munitions are expended freely by a great number of troops, not a seasonal low intensity conflict.
My thesis is that you would have done the same if you ruled the US, because it makes sense, sometimes strategically, but more often politically.
- If I'd rule the US (not gonna happen I wasn't born on US soil but let me dream further), then probably I'd consider it earlier. But yes, that makes sense strategically and politically only... they should have done it in 2011... As public opinion demanded. I get it was enough for Americans but those feelings reached their critical mass when? This year? Last year? Or several years ago?
- I consider your thesis/alternative equally plausible and not necessarily tightly related to the... let's call it for the sake of this discussion "money plot" . There are other equally influential entities to a president, congress, etc. Those shady weapon manufacturers are no longer shady nor Bond-style villains. Those are usually known to public, respectable, cold-hearted CEOs of corporations that sign huge contracts with the government, fund politicians, and so on. Those people know each other and their future relies on common relations.
- Biden administration wasn't prepared for this withdrawal at all so this was way too premature... Not to mention people, animals, the whole equipment left, and so on. That is very much surprising.
BOTTOM LINE: I have no doubt that the decision was mainly moral and political but contrasting this with expenses (e.g. "see how much we spent and for what...") isn't IMO the most fortunate as no politician (sane one) will ever admit publicly that 'War is good for business".