货币为什么会有时间价值呢?
Let's put it in this way.
You put your money $M into your bank debit account at an annual rate, r%.

After one year,
you will get M + M*r%
The additional M*r% is the price the bank has to pay.
It is the function of time.
We call it time value.
We just stop here.
Leave the purpose of bank owning your money away.

还有什么具有时间价值呢？
a. Leasing assets also has time value. such as, truck, car, plane etc.
Your payment is based on how long you are going to use the property.

b. Labor has time value too.
Employer pay salary or wage to employee for owning their time.

c. some ancient collections have time value.
Their value is heavily based on their history.

Unfortunately, for the majority of the commodities,
their time value is negative.
With business keeps updating their product,
the obsolete product has to be sold at discount rate.

任何资产，包括房子、电脑、桌子等等，只要是人们要的东西，为了延迟消费必须付出代价，这个代价就是利息，与货币是否存在无关。如果今天你借我一个苹果吃，明天还给你必须要比一个苹果多，就是这个道理