Since the market is made by each of the participating banks providing offers and bids for a particular currency, the market pricing mechanism is based on supply and demand. Because there are such large trade flows within the system, it is difficult for rogue traders to influence the price of a currency. This system helps create transparency in the market for investors with access to interbank dealing.
However, being able to push this fear aside and work through it is absolutely vital for any trader who wants to be successful. Practice trading, make notes, research new strategies and make mistakes. Trial and error is a massive part of the Forex learning curve, and generations of traders have proved that this is the most effective way to eliminate trading fears.