cryptocurrencies are prone to speculation, which makes building a system of more or less stable exchange rates very difficult. another problem is the inequality of distribution: many cryptocurrencies are held by only few people. as an example: about 1.000 people hold half of the total amount of bitcoins in the world. this means that if any of these people start using the bitcoin that they own, this will have an effect on the exchange rate. it also means that these people have a great influence on the value of the currency and are able to change its value easily. the currency itself only tells you who owns it. exchange rates of cryptocurrencies are established outside the system. exchange rates are given by brokers and traders. what they say is no guarantee that the currency is traded at the value proposed. in itself, the unit of cryptocurrency has no value.