The problem is you don't know which coin will be bigger in the future. If you talk about Bitcoin, it won't give high ROI in the short term. It will grow over time and I agree with the DCA method. If he can accumulate more Satoshi every week or month, this is the best thing he can do with his money. But, he is talking about Trading here. $20 is small to start with. But, he is a beginner and likely to lose this money. If he is lucky, he can multiply it. Everyone has to start at some point. Starting with $20 is not too bad. This is a learning process, sometimes you can't compare profit or loss with the learning process.