Why is Sansar a dream?

Gains in a dream remain in the dream.
As soon as the dream breaks and we wake up, all “gains” disappear.
And we are ok with that, because we know that it was a dream.
But we live in Sansar and it appears real.
Gains also appear real and losses also appear real.
How can we call Sansar unreal?
How can we call it a dream?
 
Whatever we gain in the dream, we enjoy it IN the dream.
So, Sansar is no different; the gains of Sansar, we enjoy IN the Sansar.
The problem is, for dreams, we have a waking state ( that can tell us every day that it was a dream ), but for Sansar, there is no waking state except enlightenment.
We should realize something –
The dreams and the Sansar both have one thing in common – their nature.
And that nature is impermanence.
And no one can change their nature.
If we always keep this in mind, we can make changes on our spiritual path.
As soon as the Sansar entices, aggravates, or insults us, etc., if we can shrug all that off, we can keep watching the dream called Sansar and stay awake at the same time.
Whatever we are collecting ( and enjoying ), losing ( and regretting ), boasting about, or running after are all impermanent and have no permanent value, just like all the products the dream offers; they also have no value.
 
Only when the permanent self is realized ( waking happens ) impermanence becomes obvious.