I believe HUD has value for some buyers but not a lot of them. With the Tesla model of having standard hardware in all cars, and turning on features via software, it may not make money sense to install the hardware for only a few buyers. However, I'd buy if it was a factory option on the Cybertruck.
I have an aftermarket HUD in both my Jeep and in my Model 3.
I use it all the time in the Jeep and love it. The factory speedo's font is too small and it takes several seconds for my eyes to read the speed vs. a bit faster on the HUD.
I very seldom use it in my Model 3. I find I usually use AP for the majority of my daily drive. Looking at the factory centre screen is more convenient while I scan my surroundings vs. looking and focusing dead ahead. But I keep the HUD installed for when I want to push the car and really drive. It's easier to read my speeds when I can't take my eyes away from the road.