They have been fighting on their own behalf. We have helped them with logistics, weapons, and intelligence to eradicate a common enemy, i.e., ISIS.
The Kurds have been seeking an independent state for decades. There are Kurds in Iraq, Iran, Syria, Armenia, and Turkey.
I agree that their main goal is independence but they have been useful in many of our own battles as well. It would be shameful in my opinion to abandon those of them who are true friends.