I don’t understand your confusion. For a person who aims to murder somebody, completing the murder is success.
Good point.
Actually, wouldn’t it be true that a desire for failure (whether in the forms of death or simple lack of attainment) would be actually contradictory, in that the attempt to fail should not be successful by the actor’s own admission (talk about a 180 from my previous conception)?
This actually brings up other questions like, “if the above is true, then is success really simply the opposite of failure?”. For if it is the opposite of failure then it follows that to succeed is to fail at failing which makes success a mere species of failure instead of something distinct.
But if that’s too philosophical, I still don’t think that praexology alone can tell us about economic success or failure because the definitions for failure and success are simply too broad and so they, as you mention, apply equally to murder as to buying/selling. So all we can say is that success for one person can be a failure for another etc.