It helped me out by opening my eyes to investing and pretty much humanity. Particularly how things can gain or lose value based on people as a hold.
Since your friend is going to be a massive newbie, I suggest he only invest a little here and there, since he will be more prone to lose it all.
Individuals make money in cryptocurrency in so many ways, Some make cryptocurrency providing value for others in exchange for crypto currency like coffee shops which accepts bitcoin as payment. Some make cryptocurrency by illegal means like the Wannacry malware that ransomed people's important information in exchange for bitcoins, There are so many ways because after all cryptocurrency virtual money and similar to how you make your regular money online you can earn cryptocurrency the same way too.