It's a cultural reason that the Pashtuns will always be victorious in Afghanistan, there is no security betting your money on Tajiks/Hazaras unless you're going to provide boots on ground military support.
In Afghanistan, Pashtun society is incredibly tribal and they are collectively raised on hatred backed by a mix of nationalism and Islam, hatred towards Pakistan, Punjabis, Gul Khans, Tajiks, Hazaras, etc. They are willing to be absolute savages and brutes to achieve their objective, the amount of deaths doesn't matter, hence why they are even ready to blow themselves up.
You cannot kill the Taliban, because effectively the ideology of the Taliban lives in pretty much all of the Afghan Pashtun population, if push comes to shove they'll always have mass recruits ready.
On the other hand Tajiks and Hazaras are generally more educated and don't harbour this level of hatred, therefore they can't maintain much loss or have the will power to blow themselves up constantly to achieve the objective. It will break them quickly.
The very fundamental goal the US was trying to achieve was against Afghan principles on a foundational level.
*No one* accepted their narrative. Their mistake was thinking they'll go in and kill the existing talibs and declare victory, but you cannot kill an ideology, that ideology lived within nearly every Afghan Pashtun very strongly, hence the Taliban had a massive recruitment pool, and that's why the US was never going to win.