If you want to sell the tokens, then sell them right after entry into the exchanges. Further the price of them only falls. Seldom what project manages to hold or even to raise the price of the token.
Your statement is simply not true. Many tokens has perform well after hitting the market. I am sorry, that you did not have any successful tokens. The most important is how is the project doing, is it moving forward or it is going down. If I decide that the project is promising, I will hold as long as I believe that I see progress.