This is because there is a great rule: When one relies on his abilities and hishtadlus, it doesn’t help; it actually makes matters worse. When one relies solely on Hashem, that's when the salvations occur.
The Chovos HaLevavos (Introduction, Shaar HaBitachon) writes, "If he relies on his wisdom, plots, physical strength, or hishtadlus, he will work for nothing, he will become weak, and his attempts will fall short of bringing him what he desired to attain... When he relies on his wealth, it will be taken away from him and given to someone else."
The Kedushas Levi (Chidushei Agados) writes, "When one relies on some matter from this world, it demonstrates that he thinks that matter chalilah has the power to help without the Creator. This causes the matter to be detached from Hashem. I heard this from my teacher, the renowned holy tzaddik, Rebbe Ber, the Magid of Mezritch zt'l. He explained the pesukim (Bereishis 36:32-32) ...וימלוך וימות, 'He died... He became king...' When a person trusts in something, he has made that matter his king and detached himself from trusting in Hashem. This will cause that he will receive less parnassah. Therefore, it states וימת [which means that he loses out]. But when one trusts in Hashem alone and places his trust in Him, and he understands that nothing has strength without the Creator, yisbarach Shemo, he attaches everything he does to the Creator. And then there will be blessings in all of his deeds because he attaches everything to Hashem."
The Gemara (Gittin 7:) says, "If a person sees that his parnassah is limited, he should give tzedakah." It is known that tzedakah is mesugal for parnassah. The Kedushas Levi explains that when he gives tzedakah generously, "he is showing with his actions that he doesn't trust in his money. On the contrary, he trusts in Hashem. This will cause that there will be a brachah in his money. Wherever he turns, he will succeed and have an enormous amount of property." This is the meaning of the pasuk (Mishlei 11:24) עוד ונוסף מפזר יש, "There is one who scatters [his money] and he is given more."
Similarly, Pharaoh had this dream for two years so that the moment Yosef perfected his bitachon, he would immediately be released from prison. The Imrei Pinchas writes, "This teaches us the greatness of bitachon. Hashem prepares a person's needs before he has bitachon, so that the moment he acquires bitachon, salvation will be available for him. This is what happened to Yosef. Initially, Yosef trusted in the sar hamashkim and was punished. He remained in jail until he had bitachon. Hashem sent this dream to Pharaoh every night for two years, so Yosef's redemption would be ready the moment he trusted in Hashem."
5. A grandson of the Tolna Rebbe zt'l told his grandfather about a person who had lost his parnassah and asked him to daven for him. The Tolna Rebbe replied, "Every Yid must believe that his parnassah is earned in accordance with Hashem’s plan. When a person forgets this, Hashem causes this person's source of parnassah to dwindle and become less reliable. If he wakes up and realizes he must trust Hashem, his parnassah will become stable again. But if he still doesn’t get the message and still thinks that his parnassah is due to the work of his hands, Hashem takes his parnassah away from him. Now, he knows that only Hashem can help him. He turns to Hashem for help, and Hashem arranges another parnassah for him. But the best path is that even when one has stable parnassah, he remembers that the parnassah isn't a result of his work, and it isn't from my boss but from Hashem alone. There are wealthy people who say המן פרשת every day, so they should remember that their parnassah comes from Hashem and not from the work of their hands. They daven daily for parnassah because they know parnassah is from Hashem, and Hashem gives them wealth and abundance. Tell this to your friend, and tell him that even after he has parnassah, he should continue to remember that parnassah comes from Hashem alone."
The man found a new source of parnassah and, indeed, didn't forget the Rebbe's counsel to continually daven for parnassah. (נפשי ישעשעו תנחומך p.749)
The Noda b'Yehuda (in his sefer Ahavas Tzion, Drush 5) teaches, "All coins, old and new, are round. Perhaps the reason it was established thousands of years ago to make coins round, and no other form, is to hint that money keeps rolling and doesn't stay in one place. This reminds a person to trust in Hashem regarding his wealth...."
