Answer:
I run smoother than any rhyme, I love to fall but cannot climb. What am I?
I am the noise Santa's reindeers make
cats and deflation tires make this noise.
I dig out tiny caves and store gold and silver in them. I also build bridges of silver and make crowns of gold. Sooner or later everybody needs my help yet many people are afraid to let me help them.
Golden treasure I contain guarded by hundreds and thousands. Stored in a labyrinth where no man walks Yet men come often to seize my gold. By smoke I am overcome and robbed then left to build my treasure anew.
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.