I'd assume you are talking about drawing, but it does apply to other forms of art.>Is it a waste if no one sees your art, regardless if it's good or not?
By drawing I improve myself as a human. It is not a waste if no one sees it, as I gain the ability to draw better and slowly master my skills. My goal is to become as good as I can, not to be an attention whore.>Do you believe it is an obligation for it to be seen by other people?
I'm on the shy side and think that people don't wish for art to be shoved up into their faces, so I don't consider it an obligation.
Also I'd like to say that art is a social construct; it's concept that only exits in our heads. Without humans there's no art, as humans are the ones that classify what is considered art and what is not. People might see abstract paintings and say that it's not art, but that's fine. There are some who may not be able to say that a painting made by shitting the paint out of your anus is art and it's fine too. Though even nailing your balls to the ground in a public place can be considered art by the other part of the crowd.
The art is any form of human expression that can be considered valuable by you, or the others.
Anything made by humans directly, or as a product of an algorithm made by humans can be art.
There's no objectively good art, but you can try to compare it based on some subjective criteria.