To be frank, airdrops are a waste of time if you participate in all, yearly, there are 0.1% of good airdrops.
Now Bounty hunting is becoming the same, you can only get rewarded from a Bounty at an average of 5/100 Bounties.
The best way to earn is to join selective bounties and do your best to earn good amount of tokens.
Remember, the higher the no of tokens, the higher the chances of earning lots of $
Currently I see there are quite a few good bounty, most of them have been listed at the exchange. So your assessment is skewed from reality. Take the opportunity and participate in bounty right now, I believe in the next 4-5 months you will get a lot of successful projects.
Joining bounty campaigns could really help us to earn cryptocurrency without any investment. Good thing that there are still projects who are good enough to give you good rewards. Always take every chances and opportunity even it is a small amount of money because maybe in the future the coin that you are holding would increase.