It's likely because they see of Bitcoin, Ethereum's Ether et al - that are also structured as Pyramid-Ponzi schemes, incentivized crypto-assets - and they see their success and figure they have a chance riding to the top in the next one that gains momentum or goes mainstream.
Bitcoin et al of course don't outright make claims of returns. Their communities with vested interest have gained enough size and attention that they gained traction in mainstream media, and that community has been "smart"/clever enough to not outright market it as a Ponzi scheme - where they whitewash with marketing hype for anything but, and where they rally to "HODL" when the crypto-assets they own are either a) on a downtrend (to help reduce a massive sell off), and b) at highs (to avoid a massive sell off) - all of which to show how illiquid these crypto-assets are; https://hackernoon.com/analyzing-every-reddit-comment-mentio... - a blog post by a company who allows bot-based buying/selling based on these HODL patterns...
There will be other tricks this organized community are surely doing now, like aligning big buyers with big sellers, so the value won't tank when someone wants to buy $100MM+ worth of the crypto-asset; all of which will lead to the perception of it not being so volatile.
This is the best wolf-dressed-in-sheep-costume that's ever come into existence.
I believe non-incentivized crypto-assets will win out in the end anyways - that is if blockchain is even a necessary part of a solution - as incentivized crypto-asset structures will cost society more (in the short term and long-term, anyone who "buys in" past a tipping point anyway), and so platforms that compete with incentivized crypto-asset powered platforms simply have to educate users/market to compete with how their wealth will be unreasonably/unnecessarily reallocated weighted towards the earlier adopters.