The ultimate way to gradually bounty scam go away is by controlling ourselves to be involved again and get trap by the scammers. Its definitely our responsibility to avoid those scammers and no one could tell us that this bounty campaigns was a scam or else but its our sole responsibility to know it. In fact, if we were never do it those scammers will just keep on smiling and waiting for an instant money while we are hoping for a false promises of those scammers.
but they will not decrease. scammers will continue to exist even if we don't choose them. but if you look at the current bounty hunter character it will be difficult to carry out what you say. many people only choose projects by origin.