Joining in Bounty Campaign can be consider as an investment because the project that launching the campign is still in the initial phase.
Yes you have a point, it can be an investment for bounty hunters it has a risk and if they managed to participate on a good campaign they can earn good profit since not all projects can be successful in the future majority of the projects that runs bounty campaign are useless projects and just wanted investors and probably end up scamming their investors.