Wagner is the only one involved and isn't really a random mercenary group though. Prigozhin is (was) in Putin's inner circle and Wagner was a tool of the Russian government. I don't think this is all that different from a faction in the armed forces trying to stage a coup as happened during Soviet times.
Of course when nukes are fought over it is always scary anyway which is why the USA didn't really want the Soviet Union to fall apart either.