I've been in a few conversations that resemble the scam one you just mentioned and there were scratched heads wondering how it was sustainable. Not necessarily scammy, because there are some legitimate chains and tokens that have roughly the same APR. Cosmos (ATOM) has just under a 15% APR on staking (where I do it anyway) and it is vibrant. Can look at others here if you have time and want to see. You'll notice that HIVE and HBD isn't even on that list.