Imo,
Biden was handcuffed by Trump's surrender-deal with the terrorists.
This same
deal killed the moral of the legitimate government.
The one entity standing between them and an overpowering terrorist force, just handed the terrorist a green light and keys to the city.
So since the U.S. was suddenly supporting terrorists in 2020, and essentially handing them the country, many of the lawful leaders and military left shortly after the U.S. started shutting down operations.
Biden had two choices: see it through, or fight it.
Had he fought it, there would have been a large body count, and lots of collateral damage. Trump and his ball washers would have been screaming how Biden fucked up a
peace deal.
The same people that believe the space lasers, pizzagate, magnetic vaccines, etc., would certainly believe this, yet another one of Trump's thousands of lies.
So Biden saw it through.
Even now, Trump is still fucking the U.S.
Trump’s Deal With the Taliban Draws Fire From His Former Allies
https://www.nytimes.com/2021/08/19/us/politics/trump-biden-afghan-taliban.html