I think there are two main reasons for the disruption of projects. Firstly, it is probably because the amount of tokens they sold when the ICO started was not enough to continue their project. They can still pay bounty hunters exactly for the tokens they earn. However, it cannot go on any exchange or its price is very low. It can be considered that the project has failed.
The second reason is that they do not know how to control time points so that bounty hunters can use the tokens they receive to trade. I think this is very important. Most bounty hunters will sell their tokens as soon as they receive it. That makes the price of tokens very low and makes the project fail