Seriously though what the fuck is a pound or a mile actually supposed to be, guys? Or cups? Gallons? What's the significance or relation of these to any of the other units of measurement? They're just words. Random words that means nothing unless you measure things stupidly. Because you're stupid. It's stupid.
In the metric system, everything uses the same prefixes that mean the same thing no matter what your unit of measurement is, and they use base10 like sensible people too. It's always consistent. A thousand grams of something is just a kilogram, because kilo- always means "a thousand". Similarly, a kilometer is just a thousand meters, not 5280 feet in a mile or some other stupid bullshit like twelve inches in a foot (as opposed to 100 centimeters to a meter, because centi- means a hundred).
I mean, what the fuck is an inch even? I get why you might measure things based on the length of your feet if you're primitive a.k.a. stupid, but then dividing that already inconsistent measurement (yes people do have different sized feet, surprise surprise) into twelve smaller units instead of some cleaner, easier number like five or ten is just dumb. It makes larger units of measurement incredibly awkward to translate into inches and back, and it sets a precedent for all your units of measurement to be totally arbitrary in regards to one another. An inch has about as much relation to a yard as a foot does to a mile. None of it makes any fucking sense!
tl;dr nano/giga will always mean a billion of a something and that's the way I like it