If you buy and install a brand-new chain, but never clean or lubricate it, what will happen?
Higher friction (comparing to properly lubricated chain) between chain pin and inner plate will make groove in pin surface faster, resulting in chain prolongation (a.k.a. chain "stretching").
Non-lubricated chain will be more exposed to corrosion.
Higher friction between the chain rollers and the chainrings will make the chainrings wear down faster.
Higher friction between all chain components will add avoidable resistance.
People on the street will look at you with embarrassment and compassion because of noise.