They are Bald by choice though man!
I bet they dont give a flying fig about baldness and hair restorers and waxes and gels either! They dont even look in the mirror cos in Pred 2 he shoved his fist through an old womans bathroom mirror!
They actually have a full crop when they are nippers but when they become "blooded hunters" they go through a "birthing" ritual where xenomorph blood is used on the head which leaves just the dreadlocks behind. The blood is acid and burns the hair off.
Jees I wish preds were really real. Id love to be reincarnated as one. All that martial skill, weaponry and all