All that ponzi are scams but not in the beginning. If you enter when they start, you can take money from them. Usually one day they stops paying and close the site like bitairy or they don't pay but their site stays alive for days (like hourlymine). If you can guess when a site like that becomes scam, you can win huge profits.
correct, they are not going to shut down the site, for a short period of time, because of course they have not got a big advantage, is very beneficial for us, if we could join in the beginning,
I often invest and if paid later run, look for other sites
