After several profitable trades, many speculators become wild and un-conservative. Traders often try to carry too big a position with too little capital, and trade too frequently for the size of the account. They fail to pre-define risk, add to a losing position, and fail to use stops. They may be unable to admit they have made a mistake, or they look at the market on too short a timeframe. They often stick with a loser until it really hurts, then take the loss.
Many traders get a fundamental case and hang onto it, even after the market technically turns.
Only believe fundamentals as long as the technical signals follow. Both must agree. Let profits run. Many people trade with their hearts instead of their heads. That's why they should have a plan first, and stick to it.