There are a few ways to earn passive income through cryptocurrency without making a direct investment. Some options include:

1. Staking: Some cryptocurrencies, such as Ethereum 2.0 and various other proof-of-stake coins, allow users to earn a return on their holdings by holding and “staking” their coins in a wallet. This process involves holding onto the coins and participating in the network’s consensus process to validate transactions.
2. Lending: Some cryptocurrency lending platforms allow users to lend their coins to others in exchange for interest. This can be a way to earn passive income without having to actively trade or manage your coins.
3. Affiliate marketing: Some cryptocurrency projects offer affiliate or referral programs, which pay users for referring new members to the platform.
4. Mining: Some cryptocurrencies, like Monero and others, can be mined using a computer’s central processing unit (CPU) or graphics processing unit (GPU), this method doesn’t require a large investment in mining hardware, but it’s also not very profitable.

Please note, that earning passive income through cryptocurrency is not without risks, as the value of cryptocurrencies can be highly volatile and there is always a risk of fraud or hacking. It’s important to do your own research and invest only what you can afford to lose.