HYIP is just a name of one of the many ways of losing money (a type of Ponzi). In short, you can safely forget about it
The problem with some sites is if the sites give high returns...they are taken for HYIP and ponzi shemes.
You can not go against the people opinion even if the people are wrong.
When people see profit ...they see just ponzi shemes...
Most of people can not imagine that a system can make profit without ponzi sheme.
The problem with HYIPs is the time to proof that an HYIP is not necessary a scam.
You can believe me:
all HYIPs are not scams...
Wtf! Then what is hyip who's not scam? Can you tell Us? Because all of long running hyips are turndown now some of thek are faking their info's and when they start so they can fool people and let's go back to your opinion then what site? I dont see any strong proof's that there are really existing and we cannot really trust when the word not scam is coming to you since you have negative trust for hyip promoting/running.