I'm one of the 3% who made over $100K (I made ~$500K).
I have to agree with other commenters that it was genuinely difficult to buy the cryptocurrency in the first place. It took me about 5 solid hours to learn how it worked, and then several days to funnel the currency through the various necessary conversions, any of which might've unexpectedly eaten my hard-earned cash for some incomprehensible reason.
In hindsight it's easy to see this as "5 hours' work for $100,000/hour, plus some waiting", but at the time there was no such guarantee of success. The only reason I persisted was because I was interested in the cryptography aspect and wanted to be a part of an up-and-coming technology.