Fear: Cutting winners short because of unwarranted fear eliminates all the big wins. Being afraid to take a good entry because of fear of loss creates a loss of a potential profit. We have to do enough homework about our trading methodology to trade our system with confidence.
Laziness: Looking to be given trades instead of doing the work to develop their own system leads to failure. Trades only have meaning inside a robust system consistently followed with discipline and risk management.
Greed: The greedier a new trader is to make a fortune the higher the probability and speed at which they lose their whole trading account. The dark side to going for the huge winning trades with big position sizes is the huge losses when wrong. Money is made in the market through managing risk so you are able to keep the profits from your winning trades. If a trader does not manage risk and position sizing their winning trades are meaningless because they will eventually give back their profits with their starting capital in the longer term.