This is a trend that happens a lot with bounty campaigns this days for blockchain projects, the truth is if a project doesn't meet its hardcap it is almost impossible to pay out the entirety of the bounty budget.
I think a change of approach should be adopted, projects should have a bounty budget that they will be capable of paying as long as the soft cap is reached.
This may mean a smaller budget but it also ensures hunters don't just join out of greed and spam repeatedly.
At the end everyone is happy
The most intelligent approach is to make the bounty a percentage of the money raised. That way you actually tie the interests of those doing the bounty with the goals of company. It used to be the most common approach to running a bounty campaign. Smaller budgets will only get you fewer participants. I know that I won't do small sum bounties unless the duration is really short (like 1 or 2 weeks) and the number of participants is small. The way to avoid spamming is to make it a fixed amount of stakes per week rather than allocating stakes for each post.