The Alter Rebbe explains that the mabul was not simply a punishment. Just like the water of a mikvah, which contains forty se’ah, the forty-day mabul purified the world from the impurities that had previously filled it.
The worries that can overwhelm a person trying to make a living are referred to as “torrents of water.” Just as the waters of the mabul purified the world, these worries cleanse him from unwanted elements.
A mikvah represents bittul—indeed, טבילה shares the same letters as
הביטל . By being batel and leaving your yeshus and self-centeredness
behind, you become elevated and can absorb holiness.
This is the real reason why a person may be inundated with business-related worries. Although they temporarily disturb and confuse him, they accomplish that his yeshus becomes broken, allowing him to be a vessel for holiness.
And since these worries are there not to punish but to cleanse, as soon as he allows them to accomplish their goal—be it in one instant—there is no need for them to remain, and he can enjoy a pleasant existence, both materially and spiritually.
Likkutei Sichos vol. 1, pp. 4–5