I think it highly depends on how well you choose the bounties you participate in. They usually pay percentage of their ICO, so the more successful project you choose, the more you earn. The rewards can thus vary widely, probably somewhere between $100 - $10k per let's say 3-months running bounty campaign.
I agree with your opinion. it all depends on us to join in the gift or other projects. indeed if you join the gift of a willingness to pay certainly also many rewards. Because of the many choices of ICO.
You can actually earn a reasonable amount of money by becoming a part of any of the bounty campaign or signature campaign and that will surely give you a chance of earning some bitcoins too. You just need to put all your focus on getting the higher ranks and that will actually help you in having greater money too. Keep working consistently as this is the most demanding thing you need to have in yourself.