It depends on how much fund is allotted to a bounty project. So many Bounties out there present only the total amount of tokens for the bounty. But if you look and convert it to dollar for example. You can see how ridiculous the rewards they are offering. It deceiving bounty hunters. Newbies are often suffer for this because they just grab whatever they can grab any opportunity to earn. So always be careful, some bounty can be a scam also. So join at your own risk.
I believe that OP main point was most of bounty campaign that he joins gives worthless tokens/didn't pay. Even though a campaign stated a 1M USD bounty allocation while it's scam then it's still not profitable.
The key point is able to have profit in bounty campaign is to make sure that the project is legit and the project objectives are unique and realistic to attain in the future when developments roll out.
The problem is with bounty hunters which didn't do research and just join whatever campaign started so in the end, their effort is just wasted and result on this kind of topic.