Jews are commanded to dwell in this relatively flimsy structure for 7 days.
It affords no protection from rain (except for a few drops), nor protection from the cold, and very limited protection against the heat of the sun. Instead of relying on our own might to create a protective structure that is impossible to fail, we rely on G-d for 7 days to protect us.
Then when we leave the Sukkah after 7 days, we bring that thought into the rest of the year: We might THINK that our homes and structures are “built to last” and will afford us protection from the elements. But the only REAL protection is from G-d Himself.
Sometimes this is obvious. Just ask the people in Surfside or Holon after their apartments collapsed.
But usually we think our homes are strong.
Just remember the lesson from the Sukkah, and that regardless of how strong your think your protection is, your protection ultimately comes from G-d.