There is a saying in the mental health field, "if you think you are crazy, you probably aren't". And, in general, I would have to agree with this. People often come to therapy concerned they are "crazy" because they need therapy. But that has not been my experience. Some of the healthiest people I have seen are the ones who recognize that something is wrong and seek to change it. Some of the sickest people I have seen are the ones who are convinced that everyone else has a problem. I often see this in families. The healthiest member of the family may be the one who is in therapy.
So... if you are someone who consistently believes everyone else is the problem you might want to check yourself. You may be the sickest puppy in the litter.
Likewise, if you consistently think there is something wrong with you and everyone else if fine you might also want to check yourself. You may be the healthy one because you recognize that something is amiss.
Similarly, the healthy folks are the ones busy working out the bugs in their system. Their energy goes into working their own program. Unhealthy folks are heavily invested in working everyone else's program.
Bertrand Russell's quote about intelligence could easily be applied to mental health,
“The fundamental cause of trouble in the world today is that the stupid are cocksure while the intelligent are full of doubt.”
Likewise, I often find that people who are uncertain, questioning, full of doubt and working on their issues are the healthiest while the most mentally unhealthy are often quite certain they are right and everyone else is wrong.