the.com/pot of gold

means An imagined ultimate reward or jackpot waiting at the end of some pursuit — often used to suggest it's more myth than destination.

from Rooted in Irish folklore about leprechauns, the mischievous cobbler-fairies said to hoard treasure and bury it at the rainbow's end — a place no one can ever actually reach, since the rainbow recedes as you approach it. The image was popularized in American and European storytelling by the 19th and 20th centuries, becoming shorthand for any prize that's dazzling, promised, and perpetually out of reach.