Can you survive normally inside an underground lavish big shelter with everything, food, recreation etc

Nope

No way

Am I alone or do I have a partner

I don't think so. Most people would break mentally at some point.

That's a fantasy the uber rich want to indulge!
They're building the bunkers and destroying our planet just to give it a try.
The book is out -"Survival of the Richest" by Douglas Rushkov.

Oh dear. I am not sure the human body is meant for such deprivation.

Do you mean like a basement apartment?

No

While standing on my head.