Euphoria is a type of greed that occurs after a trader has had a string of winning trades or a single large winner. It creates an extremely positive feeling and confidence, frequently luring you to enter and hold many new positions, usually in the same direction as the previous winner, which can lead to disaster.
This is why some traders experience their largest losses right after a good winning streak. It is very tempting to try to ride the winners wave as soon as you have made a good profit, but you must keep your feet on the ground and draw a thick line between reality and the illusion that everything you do will turn to gold.