"The value of the dollar only diminishes"
Relative to what? The dollar floats on international markets, therefore U.S. dollar's value fluctuates up and down relative to other currencies.* Domestically, however, it is a managed currency. It is managed domestically with the intention that over time its domestic purchase power per unit will decline at a targeted rate, against a background of aggregate incomes rising over time at a similar rate. This says nothing however about what we as individuals may experience.
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*this may involve more than what is immediately obvious in the case of the U.S. Dollar because of the dollars special status as a reserve currency. All currencies are to some extent managed by their associated Central Banks. The U.S. Dollar, however, enjoys some additional protection from extreme fluctuations, and in particular from rapid declines in value inherent to its special status. The world is awash in U.S. dollar denominated assets, and no central bank wants to see their dollar denominated assets lose purchasing power.