I don't believe that America is there for Afghan security but it is preserving its own strategic interests. Like having eye on the nuclear weapons of Pakistan, Containing Iran's influence, Instigating insurgency in Afghanistan, Preventing the China's rise, And exploiting the lucrative minerals of Afghanistan worth 3 trillion dollars.
Yes we need to leave and let the people learn how to take care of themselves and govern their own country. If we stay the hostility towards the Americans will get worst. We need to get out and let the problems die down and let the Afghans control their own country. The more we are there we are causing more harm than good.
The US has only the choice of staying heavily involved indefinitely or leaving altogether. We will not change the culture from their historical reliance on a warlord dominated society. Because of that, we must leave them to their own devices, as we lack the resources and the will to in effect "rule" over them. They are a long way from us geographically and are not likely to benefit or harm us to any great extent.
While it is not the best decision to withdraw from Afghanistan while there are so many problems with warlords there, it would be even worse for our forces to remain there. The United States protects and bails out so many countries under duress, that it has become difficult to help people while maintaining financial prosperity and safety for US citizens. We need to teach Afghanis how to protect themselves and then let them do the work themselves.
Labeling someone with such a loaded term as "warlords" results in a specifically desired outcome to the question. No one wants to give anything to a "warlord." If the tribal elders are "warlords" then our own congressmen could also be considered as such. Because Afghanistan is fractured into small tribal led factions, returning the land to its people means returning the land to the tribes. The tribal leaders typically control all of the finances and handle disputes. If that makes them the warlords, then yes. Give the warlords back their land that we invaded and let them get back to killing each other rather than killing US troops.
When people look at it in a negative light they're warlords, but look at it from a positive sense and they're tribal leaders. Tribal leaders are actually invaluable to the governance of the country and the rural regions, since an actual central government is very far off in the future. If ever.