OneCoin is a Ponzi scheme promoted as a cryptocurrency by Bulgaria-based offshore companies OneCoin Ltd (registered in Dubai) and OneLife Network Ltd (registered in Belize), both founded by Ruja Ignatova in concert with Sebastian Greenwood. OneCoin is considered a Ponzi scheme due to its organisational structure and because of the previous involvement of many of those central to OneCoin in similar schemes. It was described by The Times as "one of the biggest scams in history."
US prosecutors have alleged the scheme brought in approximately $4 billion worldwide. In China, law enforcement recovered 1.7 billion yuan (US$267.5 million) while prosecuting 98 people. Ruja Ignatova disappeared in 2017 near the time a secret US warrant was filed for her arrest and was replaced by her brother, Konstantin Ignatov. Most of the leaders have now disappeared or been arrested. Greenwood was arrested in 2018, as was Konstantin Ignatov in March 2019. In November 2019, Konstantin Ignatov pleaded guilty to charges of money laundering and fraud. The total maximum sentence for the charges is 90 years in prison.
OneCoin is a Scam , a known scam and one of biggest scams ... you can read all about it on its Wikipedia page