Big Russian crime groups are into large schemes and make millions if not billions each year from their criminal schemes. Such as the medicare fraud, being one of the most lucrative nowdays. And there's more, like credit card fraud and other stuff. They're into really big things, making money big. You can look at the records as well, 95% of Russians in USA prisons do time for serious crimes. In New York, there's presence of the largest Russian crime groups from Moscow, such as Solntsevskaya and Izmailovskaya for example.
They're hard to take down as well, as Russians are more less to snitch on their own people. As in our ex-USSR prison system, being a snitch equals being buttfucked for it later in prison and get sent to the "rooster" camera.
Plus mainly the members of these groups are sportsmen, such as boxers or kickboxers and others have went trough special military training or even are from special forces back in Russia.