I think to earn at least a little, you need to invest at least $ 100. Smaller amounts are simply ineffective for investment.
well if you knew that your investment will be positive investment that amount would be okay but if you are still in the process of
testing the system you can try much lower amount to make sure you understand the risk and decide whether to make more.
That is the best thing to do if you are still going to test or if you are just new to the cryptocurrency world, because if you are just going to do whatever you wanted do, especially if you are just a newbie, because the typical person here in the crypto world will just do whatever he wanted to do with his bitcoin, investing it on the HYIP sites, something like that.
But yeah, of course investing even a little will make sense than on not to invest at all, because we have to take risk for us to know what would happen next, and most of the time, the risk is the key to success.