Here's Rav Avigdor Miller on pages 3-4:
When I was in yeshiva in Slabodka — a long time ago — on the day after Yom Kippur, in the morning, the Rosh Yeshiva said a few words to the bnei yeshiva.
We were going home now; some of us stayed but most were going back now to their hometowns for Yomtiv and this would be the last talk we would hear from the Rosh Yeshiva until Cheshvan.
And so on the following morning, after shacharis, the Rosh Yeshiva spoke to all of us.
“You all labored very much on Rosh Hashana and Yom Kippur,” he said. “You put your hearts into your tefillos in the yeshiva and you were elevated and inspired; you accomplished a precious achievement. To pray in a good place these three days is equivalent to three months of learning.”
“But it is important now that you should be on guard,” he said.
“Because when you go home soon, so Yomtiv comes and then Simchas Torah; you have to beware of leitzanus.”
Leitzanus means lightheadedness, lack of thought.
He quoted to us the famous words of the Mesillas Yesharim that leitzanus achas dochah meah tochachos – one leitzanus can overthrow a built up tower, a skyscraper of over a hundred tochachos.
Sukkot also means a lot of socializing with both family & friends—which can lead to all kinds of behavior beneath Torah standards if we aren't careful.
Yet huge benefit of Sukkot is to hold on to all the good we earned from Rosh Hashanah & Yom Kippur.
The Meaning of Schach
Such a large group of a couple million people altogether, and random diseases did not spread through the group, malnutrition & hunger never appeared—nor filth or theft (despite everyone leaving Egypt with lots of valuables & sleeping in unfortified sukkahs).
So on page 12, Rav Miller states:
But you’re thinking; you look up at the schach and you’re thinking.
“Once upon a time our forefathers sat in little huts like this for forty years. And they were the safest, the most protected of any generation in our entire history because they had the ananei hakavod; they had Hakodosh Boruch Hu protecting them. In the midbar there was nothing but schach overhead and still they were more secure in the midbar than ever afterwards in our history.”
You should gain an awareness; a sensory feeling that the shechina is overhead at
all times on our nation.
And the schach is there to aid you to gain that perception that He’s watching over us.
It means we are living in a world of enemies and it’s only because we are in Hashem’s sukkah that we survive.
We always have had enemies who are talking against us, all kinds of falsehoods.
Every kind of canard, all the time.
The UN for instance even now came out with a declaration that Medinas Yisroel is to blame for shooting the Arabs.
Arabs are innocent fellows, of course. The murderous Arabs, the very worst, are poor innocent fellows and Israel is guilty. So they all came together and they made a declaration blaming Israel.
And our honorable President, maybe he wasn’t too happy about it, but he also joined in.
Now I'm not a big patriot of Israel, but we see that UN is one big gathering of anti-Semites.
They didn't even let Israel come into any one of their committees. No committee was open to Israel to become a member.
Not only in the UN. On all sides, anti-Semites are busy all the time.
There’s a tremendous literature of antisemitism and it’s been like that from the earliest times.
And still we're here.
The enemies who slandered us disappeared already.
The Greeks were the worst of all. Josephus quotes many Greek writers and their falsehoods against us. The Greeks never stopped writing against us and now they’re gone.
Greece of today is not the Greece of antiquity. Greece is entirely lost.
All their gods have gone lost. Their religion and culture have gone lost.
...the stories that we read about in the chumash about the whole nation apply equally to each person individually.
And that means that just as our nation in general is protected by the sukkah of Hakodosh Boruch Hu, in addition, each person should know that Hakodosh Boruch Hu has a sukkah around him personally.
Hashem is protecting you individually.
Rav Miller presents his own role in this as fleeting, but the truth is Rav Miller's advice both saved this man's life & enabled this positive change.
The Main Lesson to Take into the Sukkah
He explains why the Torah does that and why Rambam & Onkelos explain it away, and why the Torah does it anyway.
If the anthropomorphism woven throughout Tanach ever bothered you, these pages are good to read.
Let's go into to the holy day of Sukkot with Rav Miller's concluding words on the topic:
As much as possible, use the sukkah to gain an awareness of that great fact that Hakodosh Boruch Hu is overhead and He is the one who is guiding us and protecting us forever and ever.
No matter what the goyim try to do against us, we are going to exist and we will live longer than the gentiles.
And each person too should think, individually, that Hashem is protecting him all his life.
That’s the truth – He’s going to be our sukkah forever and He’s going to be your sukkah forever.
As you enter the sukkah, you're doing all the good things; Jewish minhagim, very good.
Ushpizin, noi sukkah, zemiros, everything; simchas Yomtiv, very good!
But don't neglect the opportunity of thinking that the sukkah now is a lesson to you that Hashem protects our nation forever and ever.
Credit for all material & quotes go to Toras Avigdor.