Chossid – It’s pashut! In Russia and Lithuania , it was freeeeeeeeeeeeeezing. SO it was sakanas nefashois not to sleep in the sukkah. Even if one were to eat there in the rain becuase of kabbala, it still way easier and safer than sleeping there! No one said to give up your life for it! Not even a Rebbe would do that,
BTW, this that chabad eats in the sukkah in the rain with a bracha, but doesn’t sleep in the sukkah even in hawaii, is a great raya to “Baal toisef, shema ba letegra.” Because it was decided al pi kabala to eat in the rain, it was decided al pi kabala to sleep inside, even in comfort.