Very well said, bounties are very risk, I even consider it gambling as well. To be honest, I joined one bounty in Aug 2018, they paid early 2019, but guess what I can't even make money out of. Although it has been listed on exchanges already, but the projects keeps on delaying and telling us that they are still making improvements and all we can do now is wait.
Bounties often have not had exact end days, companies might expand their bounties as long as possible because if you notice, most of bounties have rules for expansion. It means companies which run those bounties don't violate rule or break any type of contract with participants by expanding their bounties for a few weeks or months. Participants accept that rule at beginnings, that is also a risky rule for them.
Payments mostly delayed from time to time, when price is high, participants are not received their tokens/ coins; then when they receive tokens / coins for their works after weeks of delay, price plummets to trash figures. In some cases, no payments at all.