The artist.
 

An artist called in at his local gallery.
"Hello, have you sold anything today?"
- "Yes, I've sold the lot."
"What! All my paintings?"
- "Every single one."
"What happened then?"
- "A guy came in and asked if they'll increase in value when you die. When I said 'Yes' he bought the lot."
"Fantastic, who was it?"
- "Your doctor."

Love it. Thanks.