I remember our teachers telling us in the 60s that the US was going to begin using nothing but the metric system very soon so we had better learn it. With the exception of two or three liter soda bottles, I've done fine without it.
As I pointed out above, I started using it regularly because of one of my hobbies -- I'm an amateur paleozoologist, and nearly all publications dealing in the subject use the International system for measurements.
I was told the same thing when I was in elementary school in the late 70's.
"You better learn the metric system now, because very soon that is all we will be using."
Oh yea, I was also told, "Soccer will be bigger than football soon."
I wonder what ever happened to those old hippie teachers?
"With the exception of two or three liter soda bottles, I've done fine without it."
If you are an engineer like I am, the English system is impossible.
I, too learned metric in elementary school in the late 60's.
It's been marginally useful to me in the 40 years since.
But I never wrote love letters to it, as teachers seemed to want me to back then.
About the same time, AT&T started marketing the "picture phone." Nobody wanted to fool with those, either.
This is America, not Europe. We're the country that broke away from Europe to chart our own course, except when we go back every 30-50 years to clean up the latest Euro-mess.
If I can learn a smattering of German, French and Spanish, they can jolly well learn what an inchworm is.
FWIW, I read the other day in a Construction textbook that the reason why the US hasn't switched is because a system for integrating it into construction standards did not exist.
But, that one was being designed and was almost ready to be distributed, and that once that happend, the switch all around would happen.