Perhaps it's
an odd quirk, that a lot of people like to have things that are
rare.
At any rate, society has decided that old and rare is even more
valuable than just rare. Coins, stamps, antiques (furniture and
jewellery) and old art are collected, bought, and resold.
The point is, that certain paintings, and sculptures, may be highly
valued not because they are good art but because they are historical
and rare, just like spinning wheels.
The thousands of reproductions sold today under the banner of
collector's items, will become valueless in the future due to their
sheer numbers. They are neither original or rare.