Bounty campaign is a good way for projects to spread the word and gain publicity in the cryptocurrency market. But it is not the best way to gain investors. Good projects don't depend on bounties alone to promote their token sale.
And this is because when bounty hunters post about a project, majority of these posts is only seen by other bounty hunters and not to the real investors. And these posts are just basic and can not convince good investors to invest.
Bringing in the investors and funds depends on the team's marketing ability and their ability to close deals. This is why good projects attend a lot of crypto events and network with people.
Though bounties help a project to create popularity and hype among crypto users, the main investment and funds is brought in by the team's marketing and closing ability.
Solid marketing techniques are the foundation of a successful projects and bounty campaign is a part of it, yes it is not enough to bring a good amount of investors that is why marketers are doing some meet ups in order to gather some potential investors. And for other solid projects, they are looking for a solid partners as it can also boost their popularity among the investors especially if they can form a partnership to a trusted company or organization.
But as you can see why many successful projects are putting so much effort to bounty campaigns because it is tested already that it can help to hype their project which can help them in spreading their project in every corner of the world and the investors will surely to follow especially if they can see that the project has the potential.