I think those of us who lived it can do it, Masud. I'm not sure there are enough of us to teach others and that's the sad part. I am going to assume you are talking about 'living off the land' and surviving with what we had.
There are lots of reasons why, the first is that we have forgotten or never learned well enough to remember.
The second is that a lot of plants that influenced us, those that were used as medicines or food, a lot of those plants are now endangered and are not readily available in areas where they once grew abundantly.
And the third reason is that we are lazy, spoiled by all our years of modern conveniences. It takes a lot of hard work to be self sustaining.
We could do it if we tried. We could live off the land and be totally self sufficient and there are a lot of us who know how to do that. The real question is would others who are younger or not as knowledgeable be willing to learn?
What a wonderful thought provoking question. I wish I had a more positive answer. I do know families now, not many but a few, who are learning and teaching their children in the ways that I grew up. It will take more, more families, and more people who realize the value in it. Are there enough? I don't know.
I don't know your age, but what are your thoughts on this subject?
(Edited because I forgot how to spell.)