I would not be blaming anyone having this kind of mindset all because we know that more than the majority of these projects will eventually become worthless and die, so we might as well extract any value while we can. I am speaking from the experience here. Last 2017, I made the mistake of not letting go of my bounty rewards valued at almost $10,000 only to realized some two months later that the overall value of those coins and tokens dived to less than 15% and now if I have to look at them only one or two are still doing good in the exchanges. And this is not actually the fault of the bounty hunters, in most cases developers and project owners are the ones dumping their tokens.
Sympathize with you, I am also in the same case.
We all know that there are several scenarios with tokens after the bounty campaign ends:
1. Project failed or scam;
2. The project continues to exist, token is not listed anywhere '
=> In these 2 cases, we cannot sell tokens.
3. Token is listed, the price is higher than the Token-Sale price, then gradually decreases or has a variable price depending on market demand;
=> We can sell tokens any time we find that the value is enough to satisfy our expectations. Everyone wants to sell tokens at ATH but no one knows where ATH is.
4. Token is listed at a lower price in Token-Sale;
=> in this case, the majority of hunters decide to hold the token waiting for the price to rise again.
Obviously: any project has both potential and risks. The hunter should sell tokens when he is satisfied with the reward. In the case of the hunter having the ability to analyze the project, he can either wait for the next bull run or sell as soon as he realizes the project has no potential.
And I don't think the main cause of the token price drop is from team members selling tokens (except for Ripple). Perhaps this comes from the status of the project, the media campaign & community expectations.