Some people, such as bitcoin developer Gavin Andresen, have expressed concern that some cryptocurrencies might be scams.[23]
Some have expressed concern that the smaller cryptocurrencies are pump and dump schemes.
Some of these coins are pre-mined by parties affiliated with coin, have hidden launches, or have erroneous rewards for the first miners of the coin.[24][better source needed]
Many smaller cryptocurrencies have very few users and are only traded on cryptocurrency markets.