I don't think it's fair to require that 100% of customers fully understand the terms up front. You can't expect 100% of people to understand anything at all, since there exist some incredibly unintelligent people.
But as I said previously, a person sending money to a casino site who doesn't understand the odds will have the exact same chance of their bet winning or losing as an experienced gambler placing the same bet. People who don't understand Ponzis don't necessarily have to be stupid, they may have had google translate fail on them and be unaware that their late-to-the-queue deposit it almost bound to result in them being the one who loses their funds.
The quote about it being illegal to run a business where the income is only from new recruits doesn't apply I think. Ponzi schemes aren't generally funded by referrals, and many players player repeatedly. Obviously if nobody was ever "recruited" into playing a Ponzi then there would be no business, but the same could be said about any business. If a store never "recruited" any customers they wouldn't make any sales. That's not what the law is talking about. It's talking about schemes where you have to buy a membership to get involved.
This is an incorrect assessment of the legal condition of a Ponzi scheme.
From the Encyclopedia of Fraud:
“A Ponzi scheme and an illegal pyramid scheme both use new investors’ money to pay earlier investors. The difference between the two lies in the way each scheme is promoted. Illegal pyramids generate revenue by continually recruiting new members. The promoters may offer merchandise or services for sale—or may not—but the only significant revenues come from recruitment. Though a pyramid-style compensation plan is not illegal, it is illegal to run a business in which recruiting new people generates all of the funds.”
They are not referring to members of that Ponzi being paid referrals for 'recruiting' new participants, they mean the operators of the scheme need new people to join and send their money in. An 'honest' Ponzi scheme generates all of its funds through it convincing new people to send it money, even if it is telling them exactly what it is, the above makes it perfectly clear that it is illegal to run a business which operates that way.