Commentary for Ecclesiastes 5:12

Wealth preserved by its owner to his own detriment. Like the wealth of Korach, because of which he became haughty and descended into the grave.²⁰Alternatively, a person’s wealth jeopardizes his personal safety by exposing him to robbery, kidnap, or even death. (Sforno). Or, “wealth stored by its owner,” i.e., he stores his wealth and does not spend it to aid the needy, “to his own detriment,” i.e., resulting in the visitation of punishment upon him.

“There is a grievous evil that I have seen under the sun: Wealth protected for its owner to his detriment” (Ecclesiastes 5:12).
“There is a grievous evil that I have seen under the sun”: “there is a grievous evil” – is there a grievous evil and a good evil? What, then, is a grievous evil? It is, for example, gout, poverty, debilitation, nakedness, and hunger.
“Wealth protected for its owner to his detriment” – Rabbi Yehoshua says: This is Koraḥ. Rabbi Shmuel said: This is Navot the Yizre’elite. Rabbi Yehuda said: This is Haman. Rabbi Yitzḥak said: These are the Reubenites and the Gadites. The Rabbis say: This is Job, who was rich, became poor, and was restored to what he had been. Rabbi Gamliel ben Rabbi Ḥanina asked before Rabbi Mona, he said: ‘What is this that is written: “Wealth protected for its owner to his detriment”?’ He said to him: ‘The only benefit of the matter is regarding his punishment; when a punishment of the kingdom is imposed upon him, he will give what he will give.’⁷²The only benefit of wealth is that if the government imposes a fine upon him he will be able to pay it.