I think being self sufficient means doing what you can for yourself without relying so much on outside influences.
We hunt, fish, grow our own food to supplement our supplies(if all goes well, this year did not), process our own animals, milk goats, homeschool, and generally try to do as much for ourselves and by ourselves as possible.
We only have 3 acres but that is big enough for us to achieve a lot of our goals. We are trying to teach our children and others (that are interested) life skills that have been forgotten by a lot of today's society. We just taught my BIL how to process his first deer and we have helped numerous people learn to butcher chickens. We do use technology and I wouldn't dream of living without our computer or cell phone but that goes hand in hand with today's lifestyle.
My whole thing is that we want to be able to live somewhat comfortably if things got so bad that we could not afford to buy what we needed. If my husband lost his job then could we eat for a while on what we have? probably
I also think self sufficiency means being resourceful and learning to use what you have to get by if need be. There are some of us that couldn't afford to buy meat if we couldn't hunt, or buy "fresh" veggies if we didn't have a garden to produce our own, or buy raw milk if we didn't have a cow or goat to milk ourselves, and we also produce some of our animals' feed ourselves. Could my animals live a decent quality of life if I couldn't afford to buy feed for a while....probably.
Self sufficiency can come in degrees....it is not just people that live on acreage. People in the city can be self sufficient if they adopt some alternative practices. I think people in general are fed up with the quality of our food, clothing, and supplies in general and are looking for alternatives to have things that are better for them and their families. Goods produced now in this country don't last anymore....lots of people are buying "antique" tools and machinery because they have lasted 50 years or more and are made better than the crap that our country now produces or, more likely, has had made overseas and shipped here. People are looking to farmer's markets more and more now to buy quality food without all the preservatives and chemicals that are applied to food so that it may be shipped from other countries and last long enough to make it to where they are. There is a huge resurgence in handicrafts and buying and using recycled goods.
All of that contributes to the self sufficiency of the nation when we reduce our dependence on foreign countries for our goods.