There's quite a difference between high ROI MN/POS coins and an actual pyramid scheme. Having said that, most of the high ROI coins lose their value over time as more people get involved - like right now, the bottom performing coins (by price) on masternodes.online reads like the top of the same list ordered by ROI ~ 2 weeks ago. Which isn't to say that high ROI MN's aren't good investments - especially if you get in super early (preferably at mining stage).
For me a high ROI coin needs to fluctuate the rewards to keep the value up, and additionally should have some real world use cases (preferably different ones to other coins) and a decent roadmap. Coins which only have ROI or MN's as a USP are lining themselves up for the largest drops in value.