Its because people wish fast money, they jump in trades to fast and get out with first trouble. Getting out is how people lose money with trading, you need to know when to buy and sell, that is first trading mistake that many newbies make. Definitely as a trader losses would be incurred  even professional traders also incur losses in trades but it is always advisable to trade with  the amount of money you can afford to lose and it is usually advisable to put a stop-loss to your trade