I think it is a high risk high reward system. For some there is very little risk in investing several thousand dollars, that is a pay check or 2. But if things go well the reward could be your money quadrupling or more.
This applies to all Ponzi schemes. And despite the solid investment case most people end up holding the bag.
It just non-stop amazes me. There might be some psychological defensive-bias at work here, but just in these replies to my original comment... it's predominantly pro-btc.