From Ohr Avigdor Shaar Bitachon by Rabbi Avigdor Miller
It is easier for a poor man to have trust in Hashem because he has no other means, but a wealthy man is inclined to trust his power and influence. It’s not easy for a wealthy man to have trust in Hashem.
We are all wealthy to a certain extent, because we have access to shops with food and clothing. We naturally think that if Hashem won’t help us, we will just buy what we need. If that takes more money, we will go out and earn it. That attitude of materialism is like a wall (mechitzah) between a man and Hashem
In the minds of most people, Hashem does not have any part in their lives
He has to knock down that wall of materialism and know that Hashem not only participates in providing whatever he needs in his life, He is the sole One Who supplies anything. Without Him nothing can take place.
This may seem so simple and self-understood that it’s a waste of time even repeating it. But the truth is that in the minds of most people, even the first step hasn’t been completed. Hashem does not have any part in their lives. They’re willing to throw out a few words of encouragement to Hashem, praise Him and thank Him, thinking that it may help, but in their mind the things that really help are the physical ones, the material ones. Now we’re talking about people who believe in Hashem. They actually know that Hashem does help, but that’s not enough. They must convince themselves that Hashem is the only Source from which the help can come.
If a person trusts in somebody besides Hashem, then that trust is not a full trust. Even if he trusts in Hashem, but in the back of his mind he is thinking that in case Hashem doesn’t help, maybe his rich uncle will step in and come to his aid. But if Hashem doesn’t want him to be helped, He makes sure that the rich uncle won’t help either. We have to realize that the author is talking about the perfect form of bitachon, in which 100 percent of the person’s trust is in Hashem alone. But we shouldn’t deceive ourselves. For us it would an achievement, a big mitzvah, to partially trust in Hashem.