Lets remember that sustainable and self sufficient are two different terms.
A practice is sustainable if it can be continued indefinitely without detriment to the environment or whatever system it is part of.
That's my roommate. He's kinda weird, but he always pays his half of the rent. And he gave me this tiny ad:
100th Issue of Permaculture Magazine - now FREE for a whilehttps://permies.com/goodies/45/pmag