OK, it's true -- jpeg only degrades when it's saved. Copy it first, then edit that one. (Because you NEVER forget, do you?)
But RAW (NEF in Nikon) is much more than that. Why do you think there are 20MB in a full frame file instead of 5?
Using a non-destructive editor/manager like Lightroom, you have unlimited possibilities with RAW/NEF. Edit the B&W version, the color version, the infrared version, no problem.
You can't white balance a jpeg. You CAN White balance a RAW file.
The full dynamic range of your camera, the possibilities of the lighting, all captured in a single file called RAW.
vs.
The rendering of aforementioned data by your in-camera processor adding varying degrees of sharpening, vivacity and color balance.
It's simple.
Just take your pick!
;-)