All the Meforshim say that the Yom Tov of Sukkos represents Bitachon. We leave our strong protective homes for a shaky Sukkah, in order to be under Hashem's protection [S’chach].
S'chach means to have more shade ] צֵל[ than sun. Chazal say: ה' צִלְךְ Hashem is [like] your shadow. If you give it a finger, the shadow gives you back a finger. If you give it a full hand, it gives you back a full hand. The more a person has Bitachon, the more Hashem helps him.
We devote time to make a Sukkah and buy the Arba Minim. If we invest time for erasing our worries and fears by learning and talking about Bitachon, our Yom Tov will be complete. The main part and the Neshama of the entire Yom Tov is Bitachon. That's why it is Zman Simchaseinu, since the real and best Simcha comes from working on Bitachon in Hashem. The Gr”a said that the hardest Mitzva of Sukkos is not to have any worries at all throughout the Yom Tov. Whether you “feel it” or not is irrelevant; just working on it already gives the utmost reward.
A woman was told by doctors that her husband was terminally ill, and it was impossible to save him. Rav Elyashiv Zatzal ruled that she may not take a plane to the US on Shabbos, since it's hopeless.
But the woman came back again and told Rav Elyashiv that one day she wants to be able to tell her children that she had tried everything she could to save her husband. So Rav Elyashiv told her to get on a plane to America immediately, although it was Shabbos. They flew to America, and the doctor's saved her husband's life.
Later, they asked Rav Chaim Kanievsky Shlita why Rav Elyashiv changed his mind. He replied that the first time he thought he was speaking to an ordinary woman, and it's forbidden to be M'chalel Shabbos when there's no hope anyway. But the second time she came, he realized he was dealing with a real Ba'alas Bitachon, who doesn't give up hope.
We see from this that a Baal Bitachon has different Halachos than regular people.