This is not as simple. Users are being involved in a project for months and the tokens generally falls in price when they are listed on the exchange.
There are many reasons why a bounty has large number of participants while some have few. Some do have a cap on number of participants.
The obviously legit project that has no cap for participants number are flooded with bounty hunters.
Simply because that bounty pool is small, but the bounty hunter realizes that the project has a lot of potential when going to exchange. Like the GowithMi project that I have seen before, pool bounty is very low. But now its price is x10 compared to the IEO price