Is 'negging' actual a thing?

Negging is a conversational tactic used to undermine a person's confidence through a backhanded compliment or subtle insult. The word is a portmanteau of the words "negative" and "beguiling," and the goal is to make the other person feel insecure and seek your approval.
A neg is not a direct insult. Instead, it's a statement that contains a compliment but is framed in a way that minimizes the person. The goal of a neg is to make a person feel like they need to prove themselves to you.
Examples of Negging
* "That's a nice dress. It's a shame it doesn't really fit you."
* "You're a pretty good cook. I didn't think you'd be able to pull this off."
* "You'd be really pretty if you just changed your hair."
Why People Use Negs
Negging is often associated with pickup artistry and dating advice. The idea is that if you make a person feel insecure, they will lower their guard and be more receptive to your advances. It's a tactic that is manipulative and can be emotionally damaging.
If you believe someone is negging you, you can respond by calling it out, ignoring it, or walking away. In a healthy relationship, a person should build you up, not tear you down.

Very effective turn of the century/ early 2000’s pick up technique .

Yes