It is not so, because humans have finite life span. So they MUST spend their coins within a fixed time frame of about 70 years.
As more goods get made relative to bitcoin, and more people come to exist, the prices of goods & services must come down relative to bitcoin in order to avoid liquidity crises - especially since the number of bitcoin is set to be capped (while population and goods aren't). Bitcoin instead was designed to handle this problem via trading in fractions such as satoshi's.
Not unless all economic growth stops, too. More people in the world + fixed number of bitcoins = deflation. More cars/computers/thingys made + fixed number of bitcoins = deflation.
Inheritance. Donations.
So, you do not have to spend everything while alive.