Throw more light to the associated risks involved than just the profits.
These should be quite simple things, because if you don't make a profit, the opposite is that you will either lose part/all of the amount you invested or you may end up with a positive zero. When investing in cryptocurrencies, the risks are far greater than in the case of stocks, gold or real estate, because the risk is not only in the price, but also in the way someone keeps/stores their coins, which is one of the weakest points of most investors.
How am going to convince him to buy into this strategy is what I don't know where to start from for him to believe it will work out well for some profits, and another thing is if he would have available $200 at the moment to DCA for another one year or more.
I won't conclude anyway not until I relate to him on this idea.
Are you a financial advisor or a great cryptocurrency expert? Why do you even go to such conversations, unless you want to be responsible for another possible disappointment and maybe even a financial loss? In my opinion, that person has two options - simply wait for the price to be higher than when he invested and then sell, or accept the loss if he needs the money.
Money doesn't fall from the sky, and neither does good advice, no matter how well-intentioned.