[FatherofFive]

Bitcoins will remain rare like gold; by 2040 when the world population reaches 10 billion there will only be 1 bitcoin for every 500 people on the earth.

My poop is also rare. About a pound a day. By 2040 there will only be 9,855 pounds. Rarity does not equate with value.

[GeronL]

Very true. There also needs to be demand for it.

[BfloGuy]

By 2040 there will only be 9,855 pounds.

Not to belabor the point, but unless you're freezing it, there will be none left. Gold and [we might expect] BitCoins will both still be around. Durability along with scarcity begin to meet the qualifications for value.