Nihilists say things like, "emotions and ideas are just chemicals in the brain", or "there is no such thing as truth", or "nothing has meaning unless it can be absolutely grounded", or "asking 'why?' is useless", or "you can't prove that, you're just asserting it".
I wish I could say that I feel sorry for these nihilists. But in all honesty, I do not. Maybe it is their utter contemptibleness that prevents me from feeling a shred of pity for them, even though I understand their disease and would like to help them overcome it.