Because they’ve endured the partition of their nation, sort of like if Obama gives back half of Texas to Mexico.
Oh wait, he’s already doing that.
So, how do YOU like it? Hmmm?
BS, if the Serbs wanted Kosovo, then they should have taken it. If you cant take and hold what you claim, then it is not really yours. The complaints of the Serbs on Kosovo is akin to the complaints of Arabs over the loss of Israel.