There's the guy who gave away so much gold he broke half of Africa's economy; the motivation might be different, but I think it counts if the category is "got money badly wrong".

from wikipedia:

> According to some Arabic writers, Musa's gift-giving caused a depreciation in the value of gold in Egypt. Al-Umari said that before Musa's arrival, a mithqal of gold was worth 25 silver dirhams, but that it dropped to less than 22 dirhams afterward and did not go above that number for at least twelve years.[95] Though this has been described as having "wrecked" Egypt's economy,[83] the historian Warren Schultz has argued that this was well within normal fluctuations in the value of gold in Mamluk Egypt.[96]

Seems like this might a misleading folk tale.

How about the time that Scotland got envious of all the other European powers doing colonialism in the New World, so they dumped all their wealth into setting up a colony in the Darien gap, which failed so horribly that it bankrupted the country and forced them to unite with England.

https://en.wikipedia.org/wiki/Darien_scheme