I was a salesman 20+ years ago and still engage in up selling my friends. But it’s usually to get them to engage in healthy activities like working out, going for a walk, or eating healthy; or to get them to try a new experience like tasting a new food or being more honest/kind to their loved ones.
Sometimes I wonder if I’m exhausting to them or they appreciate the good intention.
By the way: this is also a reason that I see why so many hackers date differently from the typical population since dating is about manipulating the other side to love one.
Sounds like you're doing it wrong.
Then I have to conclude that a lot of dating advice that one finds is plainly wrong: "show off your best side" is for example an instance of "manipulate the other person to believe that you are of higher value than you actually are (and thus a relationship with you is a better deal than it actually is)".
I think the hacker (non-sales) style is to lead by example, not spend so much effort trying to convince others with words. "Deeds lead" for hackers.
For example, instead of trying to directly convince a very unhealthy co-worker to eat less junk food, I might talk about my own struggles with junk food eating... or say that I am trying to cut down. Or exercise more. Or whatever. But focus on myself and my own actions and the messages they emit... rather that trying to directly manipulate the other person with words only.