I think we add our own meaning to things in the bible all the time. In fact, I was listening to John yesterday and there is a place where this happens in the bible and is called out. In John 21, it say’s this:
22 Jesus answered, “If I want him to remain alive until I return, what is that to you? You must follow me.” 23 Because of this, the rumor spread among the believers that this disciple would not die. But Jesus did not say that he would not die; he only said, “If I want him to remain alive until I return, what is that to you?”
The “thief in the night” analogy points out the unexpectedness of the event, not the impact. A home invasion comes like a thief in the night, but you notice it.
Indeed, the “thief in the night” analogy has only to do with “you won’t know when it’s coming” - but when it comes, you’ll definitely know it happened/is happening.