As of today, there are still potential income in airdrops and bounties but not the same way back 2017-2018 where in a lot of great bounties scattered here in forum. Bounties that can give you a great amount of income like 4 digits and even 5 digits in usd.
It all depends if the project is good and with a strong team behind. Nowadays most airdrops are from meme tokens to increase their holders count and even if we receive millions of tokens its just worth less than $1.
As of now, Bounties are the best way to get crypto without investing any money, Only time investment.
Yeah, time will be your capital in doing bounty. But as far as I can see, bounty campaign nowadays is being belittled by some project teams and even get scam their participants. If that incidents will continuously happen, then the credibility of bounty will loose as time passed by.