Well no, assuming "sanity" is judged here by "a lack of serious personality disorders" (and really, who amongst us can ever be called completely sane?).
As for psychopaths, well there are often considered by the psychologists who still use the term (and especially those that think it separate but related to Anti-Social Personality Disorder) to be two types: Those that blend in with society and those that don't. The latter often wind up in jail, the former in business. Anti-Social Personality Disorder is not (as far as I know) considered a valid legal defence since it doesn't strip you of your decision making skills at all.
Whilst a person with schizophrenia can be stripped of all or most of their rationality, a person with ASPD often displays significant rationality, at times displaying more rationality than a "normal" person (most likely due to the shallowness of their emotions, aside from short-lived rage they don't feel as deeply as most people so can keep their heads easier (for better or worse). It's been noted that those with ASPD are rarely affected by social panic). They have poor impulse control due to craving stimulation (which makes sense when you realise the stimulation is often all they have), but they typically are aware of the consequences of their actions just apathetic towards the effects they have on everybody else and egotistical enough to believe they can avoid suffering consequences to themselves. We all have moments of complete unempathetic selfishness like this, ASPD can be described as being locked into that for most of your life.
A psychopath can still be happy, sad, etc etc, they just don't feel those things about other people. They can also still logically come to the conclusion that needlessly harming people = bad, they just don't get the negative emotion from harming others.
Actually "shallow emotions" is one of the criteria for ASPD. Some clinicians have described them as mere primitive responses to immediate needs instead of the "deep" emotions of the mythological 'normal' person.