So my kid tells me that her teacher said my kid could teach the class. I told my kid that was great, good job!

Later my kid is talking to me:
Kid: Nerd!
Me: If I remember correctly. Your teacher said you could teach her class. My teachers never told me that. I think that makes you the nerd.
Kid: <big frown>

I think the negative connotation for "nerd" came from the dumb bullies who chase fake clout but are empty from inside.
One should be proud of being called a nerd.
Smartness and intelligence should be celebrated but in the modern era "dumb is the new cool"

@ViRaS I tell her I have a nice job because I am a nerd. Never got called a nerd in school though. But people would try and get a seat by me to copy off my math work.

@jestdotty looks like it was Dr. Seuss who made it a thing:

https://etymonline.com/word/nerd/

Basically it sounds like it was 80s propaganda to demonize people who didn't take drugs. It later morphed into a smart person. I dunno.

The media/pop culture likes to popularize things to sway the public to make poor decisions regarding their health. Weird. Remember the smoking propaganda? Then people can't make the next connection. They never stopped doing this.