I want to retract my earlier post comparing not sleeping in a sukkah to not eating cholent. The comparison is faulty and not worthy of discussion. I was short of time and wanted to come up with an explanation quickly, and I did, but it was a totally inadequate and wrong explanation.
What I should have written is what Neville wrote: There is actually a substantial heter to not sleep in the sukkah that many non-Chabad people in northeast America rely upon. The problem is that Chabad will never say they are relying on this heter. They instead created their own logic and now refer to not sleeping in the sukkah as a chumrah. They institutionalized the heter to the point that those who could otherwise sleep in the sukkah just fine don’t.”