I think you mean 1980s.Here's the hard truth, and this will be my last post in this thread:
We didn't "lose" Afghanistan in 2020 with a **** treaty. We didn't lose it in 2021 with a chaotic and rapid "Dunkirk" retreat, nor in 2003 when we forgot all about them because invading Iraq became the national obsession and they were second hand news.
We lost it in 1992-93 when we could have truly "nation-built" after the Soviets left and the Kabul communist gov't collapsed simply by sending aid and advisors that would have been welcome at that time, with minimal investment and no combat deaths. But we cut all aid and lost interest after the Red Army left and watched them devolve into civil war with a corrupt collection of pederast warlords leading to the rise of the Taliban and the Northern Alliance...
Rinse and repeat...
While true, and I think you mean in the 1980s a decade before, it was an irrelevant rock with irrelevant 3rd world people and it would have been impossible to believe in 20 years later we'd suffer 9/11/01. Nobody could have foreseen that. So an investment there would have been laughed out of the Congress. May as well pick some other 3rd world spot and dump money in today claiming it's important.
I cannot fault people in 1985 for not having crystal balls. They managed based on then-known threats and information.