Because to many people, being alone for their entire lives is already terrible. And it’s not like it’s a foregone conclusion that a relationship with a person you met in psych ward is terrible, it’s also possible that it’s good (or at least better than with a non-psych ward person) because they understand each other’s issues. Conversely, many people who never went to a psych ward also have mental health issues, which often go entirely untreated.