What does it mean to be grounded in reality?

To always see things as they really are.

When your basic views start in reality. When someone is un-grounded, that means they are cleared for take off. Getting ready for a flight. So they are flighty.

Jerry Springer’s burial.

They often seem happier with life to some degree.

Positive attributes of course.
Artists,Musicians,Writers etc do this most of the time in order to free the mind up to create.

Tolkien, Walt Disney, and numerous others channeled their painful experiences for Tolkien it was the effects of War and for Disney it was his bad childhood experiences.

They turned bad experiences into a creative positive medium ( writing a creative Fantasy, or designing a Children’s Fantasy World)

A positive antonym would be idealistic.

@LostInParadise
Exactly..as Walt Disney was really designing an idealistic world for children.