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.
Recently, almost no one earns well. It does not matter what your rank is, but the payment people receive in the last few months is very small. Because bitcoin continues to decline and because of this, all the tokens that appear on the exchanges receive a very strong price reduction. Up to 10 times less than the price that was at the ICO.
Yes I made the same observation, I am quite picky with the ICOs I invest and one is down 1/4 from the ICO price and the other one even 1/10th of the ICO Price. If it continues more people might stopp investing in ICOs and future bounty project will pay out even less than today