Short answers, pulled from the story.
Russian oligarchs were business figures from the former Soviet republics who rapidly accumulated wealth in the 1990s through privatization following the Soviet Union's dissolution. They exploited loopholes during Gorbachev's perestroika reforms and later acquired state assets at a fraction of their value through mechanisms like the loans for shares auctions conducted before Yeltsin's 1996 re-election.
The Semibankirschina, or seven-banker outfit, was a group of seven oligarchs including Roman Abramovich, Boris Berezovsky, and Mikhail Khodorkovsky who collectively controlled between 50% and 70% of all Russian finances between 1996 and 2000. They also helped finance Boris Yeltsin's re-election campaign in 1996.
Mikhail Khodorkovsky, head of Yukos oil, was arrested in October 2003 and sentenced to nine years, a term later extended to 14 years. Putin eventually pardoned him, and he was released on the 20th of December 2013. His net worth fell from a listed US$15.2 billion to US$2.0 billion following his arrest.
On the 2nd of March 2022, the United States announced Task Force KleptoCapture, a dedicated team drawing officials from the FBI, IRS, Marshals Service, Postal Inspection Service, Homeland Security Investigations, and Secret Service. The task force aimed to freeze and seize oligarchic assets linked to illegal involvement with the Russian government and the invasion of Ukraine.
Dubai and the UAE became havens for oligarchs seeking to shield wealth from Western asset seizures. Russians spent over US$6.3 billion on Dubai property in 2022 as non-resident buyers. In May 2022, oligarch Andrey Melnichenko's 118-metre Motor Yacht A was anchored in Ras al-Khaimah in the UAE, where it remained largely intact despite international sanctions.
Roman Abramovich bought 16 Kensington Palace Gardens, a 15-bedroom London mansion, for £120 million. He also purchased English football club Chelsea F.C. in 2003, spending record amounts on players' salaries.