The Gemara (Avodah Zorah 3) tells us that when Hakadosh Baruch Hu rewards the Jewish nation, the nations of the world will request another opportunity to keep the Torah so they too can receive reward. Hakadosh Baruch Hu will say, “Fools! It is too late to perform mitzvos. Nevertheless, I have a simple mitzvah, it is called succah. Keep this mitzvah [and I will grant you reward]."
The Gemara relates, “Immediately, the goyim will go up to their rooftops and build a succah there. Hakadosh Baruch Hu will have the sun shine brightly; it will become sweltering for them. They will get up, kick their succos, and leave.” The Gemara explains that although Yidden may also leave the succah when it's very hot, for the halachah is הסוכה מן פטור מצטער, someone who is in distress is exempt from succah, but a Yid never kicks the succah when he leaves. The nations of the world will kick the succah in disdain, and therefore, they don’t deserve any reward.
B'derech tzachus, we can say that they intentionally built their succos on their rooftops because they didn’t want people knocking at their door, asking for a meal. Contrarily, Yidden seek to have guests on Succos.
We can also explain this Chazal as follows: The hot sun represents the hardships of life, and the succah represents shelter and belief in Hashem. Non-Jews have emunah in Hashem so long as everything goes well. But when the hot sun shines brightly, representing difficult times, they kick the succah—they no longer believe in Hashem. But the Jewish nation believes and trusts in Hashem under all circumstances.
