The most important thing you might lose, in my opinion, is stability in your trading style. These sorts of sensations will take you out of your way and cause doubts about your strategy. If you have gathered enough knowledge on different strategies and assets, you will not be going through these sorts of emotions very often, so stay up-to-date and you will easily avoid such situations. Closing your trades before they hit their targeted TP or even SLs is one of the most obvious mistakes that could happen here.