Nobody wants a given currency per se. What they want is what they can purchase with that currency. Reserve currency status has nothing to do with whether that currency is worth anything. Every currency in the world has a market price. US dollars are worth something for the same reason that the Russian ruble, the Chinese yuan or Iranian dinar are worth something - for the goods and services produced in these countries. The US not only has an abundance of natural resources (oil, minerals, abundant fresh water, fertile land), it's also a veritable font of new technology, machinery, drugs and any number of innovations. The US dollar will always hold its own against other currencies. And that is one reason why other countries prefer to use the dollar as their primary foreign currency reserve.
Another reason is that the dollar is the highest volume currency traded in the world. This means buy sell spreads are low compared to any other other currency. Here are the relative amounts of currency traded by foreign exchange traders. As you can see, the Mexican peso accounts for 2.5% of currency volumes, yet Mexico is the most obese country, on average, in the world. Bottom line is that nobody is going hungry because his country's currency isn't a reserve currency. (Note that these trading decisions are made by people trying to minimize their transaction costs, not blowhard leaders of foreign countries who think they are the closest thing to deities currently on this Earth. They don't choose the dollar because they bleed red, white and blue - they do it because it's the cheapest currency in which to conduct international trade).
| Rank | Currency | ISO 4217 code (Symbol) |
% daily share (April 2013) |
|---|---|---|---|
|
1
|
 United States dollar |
USD ($)
|
87.0% |
|
2
|
 Euro |
EUR (€)
|
33.4% |
|
3
|
 Japanese yen |
JPY (¥)
|
23.0% |
|
4
|
 Pound sterling |
GBP (£)
|
11.8% |
|
5
|
 Australian dollar |
AUD ($)
|
8.6% |
|
6
|
 Swiss franc |
CHF (Fr)
|
5.2% |
|
7
|
 Canadian dollar |
CAD ($)
|
4.6% |
|
8
|
 Mexican peso |
MXN ($)
|
2.5% |
|
9
|
 Chinese yuan |
CNY (¥)
|
2.2% |
|
10
|
 New Zealand dollar |
NZD ($)
|
2.0% |
|
11
|
 Swedish krona |
SEK (kr)
|
1.8% |
|
12
|
 Russian ruble |
RUB (₽)
|
1.6% |
|
13
|
 Hong Kong dollar |
HKD ($)
|
1.4% |
|
14
|
 Norwegian krone |
NOK (kr)
|
1.4% |
|
15
|
 Singapore dollar |
SGD ($)
|
1.4% |
|
16
|
 Turkish lira |
TRY (₺)
|
1.3% |
|
17
|
 South Korean won |
KRW (₩)
|
1.2% |
|
18
|
 South African rand |
ZAR (R)
|
1.1% |
|
19
|
 Brazilian real |
BRL (R$)
|
1.1% |
|
20
|
 Indian rupee |
INR (₹)
|
1.0% |
| Other | 6.3% | ||
| Total[73] | 200% | ||