Can you say that these campaigns are profitable? Or have you had the chance to join a signature campaign (altcoin bounty) that you found very lucrative in the past?
The reward actually depends on how good the campaign. Sometime those bounty hunters can earn up to thousands or ten thousands of dollars from a super legit campaign. I can't even provide you some links to the old worthed bounty campaigns that gave bounty hunters lots of rewards.
I have a chance to join in some legit bounty campaigns in the past. The reward may vary depending on the price of token. We can't say how good the reward but if you are lucky enough and you can get a lot of money.
Some bounty hunters have managed to earn millions dollars through participated in the ethland signature campaign aka aave.