Many sentences require you to have some knowledge of the world to process. In this case, you need to have the knowledge that "being comfortable dictates where you sit" doesn't happen nearly as often as "where you sit dictates your comfort."
Even for humans NLP is probabilistic, which is why we still often get it wrong. Or at least I know that I do.
Although the sentence is itself a bit awkward and strange on its own, and really needs context. In fact, this is because the sentence is generated as a short example to make a point about attention and tokens, and is not really something someone would utter naturally in isolation.
I mostly just wanted to playfully comment that original GP / top-level comment had a valid point about the ambiguity!
Absolutely, but in this case and in many others we just don't have that kind of context. So we do what comes naturally and make assumptions based on past experience. We assume that the most frequently encountered form of it is the right one. From one perspective it can be said that LLM's are doing the same.
It's interesting to note that jokes are absolutely riddled with confusing and syntactically vague language like this. If you're ever looking for a good NLP test find some children's joke books. Those old dad jokes are mostly just about the vagaries of the English language and how easily you can be surprised when the "solution" to a sentence is not the most common one.