You cannot laugh at the same joke again

A wise man sat in the audience and cracked a joke.
Everybody laughs like a crazy.
After a moment, he cracked the same joke again.
This time less people laughed.
He cracked the same joke again and again.

When there is no laughter in the crowd,
He smiled and said
You cannot laugh at the same joke again and again,
But why do You keep over same thing over and over again?