Famous works of art are worth millions of dollars
because someone is
willing to pay millions of dollars for them at auction. Its not the
consensus of the dealers or critics that sets the price.
Just a general comment on "worth". There are two types here. There is the
worth or value of something to the individual. Then there is the market
worth or value, which is the price others are prepared to pay for it. The
two often match up but not necessarily so, especially if the value to the
individual is due to deeply personal reasons (taste, nostalgia, etc.)
Terry