For many of the people who don't see the great value in this domain, I wonder how familiar they are with the self-developement niche... That industry is huge, and there is so much money in it.
Various concepts of "being" are constantly used in different way, and it has so much potential in this niche. BEING could easily be used as the brand/term to describe main philosophy or concept of one of the "gurus" in the industry. Anyone familiar with this industry would see the value in this name.
"Beings" has no such use. I guess it is more commonly used when talking about "alien beings"... At least it has nothing to do with the self-developement niche.
Being on the other hand, deals with existing in the world in a certain way, and the essence of that existence. So if somebody develops a certain life philosophy/way of approaching life, they could call their concept BEING (with their website, accompanying book titled BEING, and basically BEING would be their premium brand). It would make no sense to call it beings...
Good luck with the domain
@GhostWriter. And I hope it will be acquired by someone who is the real deal, and will provide something of value, rather than the snake oil sales type of "guru".