When the prices and quantity are held constant and if the
demand curve becomes more elastic, the consumer surplus from a
product declines for a consumer.
This is because when the demand is very elastic, consumer's
willingness to pay for a particular good decreases until a point
where the amount consumer's are willing to pay equals the amount
they pay.
At this point, there is no consumer surplus and it equals
zero.
We know that the consumer surplus is the area under the demand
curve. Hence, when the demand becomes elastic, the area under the
curve when the price and quantity is held constant also
decreases.