You can't really blame bounty hunters for hating long term campaigns, of course in 2017, everyone is on the boat of the hype, so it doesn't matter if the campaign is long enough. I've seen Legendary members that time raking up thousands of dollars in a campaign that lasted months and months.
But 2018-2019 was different though, many project fails and those who survived just got a measly payment. You are lucky that you have earn on Airwallet. So it's a case to case basis, but I'm sure majority was complaining because they didn't get the money that they were supposedly promised by many project.
Generally, I agree with you.
You can't blame them because that's how the bounty work. Even after the collecting, selling is the worst way
When you enter a bounty you need to think long-term