Bitcoin doesn't and has never promised the users of their product or advertised their project as a vehicle of guaranteed profit. Bitcoin can go up and down and the ecosystem won't collapse. The 2014-15 decline of Bitcoin would have destroyed schemes like these as money was leaving the ecosystem. Money left Bitcoin for over a year, yet Bitcoin survived because of no promise of profit. Bitcoin is simply an asset like gold. It's value is determined entirely by the market, but does not rely on money coming into the asset. Bitcoin would still exist if each Bitcoin cost a penny. You can also sell your Bitcoin whenever you feel like it, these schemes usually require you to lock up your assets for some period of time.

A pyramid scheme requires constant cash flow to pay those at the top of the pyramid. If these schemes existed in 2014, they would have all fallen apart or exited because they couldn't give money out as money was leaving the space. That being said, one could argue that Bitcoin is in somewhat of speculative bubble and may be due for a significant correction, but I am quite confident that when that does happen, these schemes won't be able to survive the bear market as money will quickly exit the space and all those at the bottom of the pyramid will be left holding the bag.