What is the exact meaning of a "calculating" person?

I am not a psychologist so forgive the dumb question. I frequently read the "calculating" sign attributed to people with anti-social behavior like psychopaths, but I fail to understand what this word exactly mean. According to Merriam-Webster, calculating is "marked by prudent analysis or by shrewd consideration of self-interest". However, I am not sure I understand what exactly is bad about this. Surely we are all better off doing some prudent analysis about the situations we are in, no? Would you just jump into a job without analyzing whether it is good for you or not? How about when you decide to get married, do you just jump into a marriage without thinking about the possibility of the success of the marriage? Perhaps the second part of the definition is negative, I mean the "self-interest" part, but then this sounds like being selfish, as opposed to how this word is commonly attributed to antisocial or even criminal behaviour.

Looking at it differently, the opposite of the definition above is perhaps "marked by no analysis and consideration of self-interest." Now yes, the second part seems altruistic, but the first part is something that no one would want.

I am sure I am missing the obvious, perhaps it is because English is not my main language, so I would appreciate some explanation on this word from a psychology perspective.

Thanks