I think most of the people here have the same reasons why dumping, because it costs money or because the token doesn't have much progress (it has a small volume and doesn't have any updates)
When people are seeing the project didn't have a lot of potentials and then they will be dumping their tokens to the market. Their decision will be affected by the progress that has already made by the team and how good the product that has already released.
I would agree with you @CuriousGeorge and for me, I will also dump it if ever I saw the coin that has no potential in the future like it can't be useful to all users who have it. It's better to sell it before it loses its value in the market. However, if you a have coin that has potential and the team behind keeps on doing their best to make great development in the coin it's better to hold it than to dump it.
Probably, the immediate selling of coins of bounty hunters is also caused by the dump in the market and we all know this really affects the progress of the project. And we should always look for the bounty project who has the potential so we will not waste our time and efforts. Then, just keep on holding your coins if you see it can have great in the future.