Answer:
When artists pass away, the supply of their paintings most likely becomes harder to acquire, making their pieces of work more rare to obtain.
When an artist dies, they cannot produce any more supply of their paintings to the public market. However, the pieces that were made by the artist grow in value and rarity, considering the supply is limited.
Take Picasso for example; he mastered outstanding works of art, however after he died, his pieces grew in value considering no other originals were going to be made.
Hope this helps! If not, feel free to comment below and I'll see what else I can do to help. Thanks and good luck!
