I mean, by your logic, nobody could have predicted Bitconnect to be a scam?
An obvious ponzi vs. a mixer offering reward for boosting liquidity, which generates returns from its business, is not the same at all.
At a certain yield, such services are simply not sustainable without being a ponzi, i.e. paying existing customers from new customers' deposits.
All the crypto ponzis so far had some kind of 'excuse' of how they were able to give insanely high returns without risk and without being ponzi schemes. 'Reward for boosting liquidity, which generates returns from its business' sounds to me like it fits right in with those previous 'services'.