This is a question designed to elicit a certain response from people who think like you and earn like you, i.e., not the middle and poorer classes. We can easily imagine a family in many parts of the country that earns $45K thinking of all the things it could do with an extra $10K. The most helpful statistics in determining whether a median HH income of $55K is too little for a middle class would be a median cost of living for that same population along with some measure of dispersion. If that showed that they’re spending every dollar on necessities, then yes we have a serious problem.