We know that four way to cryptocurrency income such as Invest ico, mining, trading and Airdrop-bounty. If you wish, you can do any of that.
If you want to mining or invest in ico and need a lot of money, it has cost-effective risks and have also profits. And if you want to do trading then you can start trading only if you have some money. Here's a little less risk and have also profit.
If you do not want to take a risk then you can start the bounty. There is no risk here only you will have to work on time and you will get your payment at the end of the job. As a payment, you can get cryptocurrency and convert them into meaning by selling them. So, I think Bounty and airdrop is very good for earning risk-free cryptocurrency profit.
Well, for me, I think hodling and airdrop are two of the not-so-risky ventures one may do in the cryptocurrency market. But, since the premise of the question is a "risk-free" way, then I would say that there is none. There is no venture that one can say as risk free because everything has its own cons as it also has its pros. Also, the nature of being "risky" has always been tied up with cryptocurrency investments since the market, in general, and the assets have always carried that risk factor with it. That is the very reason why not very many can handle the market. For example, with airdrops, although you can get some tokens for free, the risk there is that it can be an act of scamming people to steal off their important cryptocurrency-related information such as wallet information. They use the cloak of getting a coin for free to entice people to enroll in it only to find out that the airdrop is a sham.