Look at the Portuguese fighting retreat from their India colonies twenty years earlier and ask what was the point of the violence? Look at the west's war in Vietnam and ask what was the point? Look at the Falklands and ask???
An alt-history counterfactual theory: if the US had not supported the Taliban in Afghanistan, the Democratic Republic of Afghanistan might've joined the Warsaw Pact and then had a peaceful revolution (like almost all the rest) around 1989, with all the attendant advantages for a better version of this century.
The following claims to be 1980's afghanistan, but I can't tell if the Boney M soundtrack was original or not: https://www.youtube.com/watch?v=SZRZLwLXU3E (Boney M was apparently popular in Afghanistan, but other videos with the same dancer are to more indigenous tunes)
maybe better: https://www.youtube.com/watch?v=LrxgwM8h7ek&t=30
(To be fair, the UK's defense of the Falklands was also hugely expensive, caused significant loss of life and may eventually have proved unnecessary, but at least it was a valid position under international law)