Yes there is way to earn crypto currency without any investment that is by participate in
Airdrop
Bounty program
Airdrop is a promotional marketing strategy which is opted by the most of the ICO to create the market hype and to enahr the community. Usually in order to participate you just have to join Telegram channel of respective ICO and by liking the social handles but it can also vary from ICO to ICO.
Bounty Program is another way of creating the market hype and engaging the community for the longer time period. In bounty program you have to promote ICO on your social handles, in depends on the participants, in which (s)he is interested. Generally it includes promotion on Facebook, Twitter ,BTT, Reddit and Medium
yes that's how I get tokens, I follow the airdrop and bounty program because even though I actually am a bounty hunter but I still can't ignore airdrop, because sometimes airdrop can also be good and can be my helper when I really need money even though sometimes only get $ 10 but it can save my life in a day, I don't really care about the words of people who think that the airdrop program is not worth it and I don't really care about the fact that there are many airdrop and bounty programs that are scam, because that's all I can do here