It’s an interesting question. If we are wondering What’s wrong? as in the general concern for someone’s welfare, we have to be brave enough to ask and to hold space for the answer (because we might not like what we hear).
However, if we are asking just to compare ourselves to someone, to poke our nose in someone’s business, that’s clearly a problem.
The act of comparison itself is often an attempt to feel better about the shortcomings we feel in our own day-to-day lives.
People sometimes can’t help but compare to others to better understand their own happiness and shun their insecurity.