There are so many ethnic groups spread out over such a large area, how is it that Moscow can keep so many of them under its control? Would Russia balkanize if a catastrophic event (like, idk a failed invasion of a neighboring country that isolated Moscow from the rest of the world and destroyed its economy) happened?
After losing WWI, a massive a bloody Civil War, and the collapse of the Soviet Union, it feels like a miracle Russia is unified. Am I missing something?
Linking to a similar previous question "Why Has Russia Never Collapsed?" with some answers by u/Lithium2011 and Yours Truly.
The TL:DR - "Russia" is a squishy concept, and depending on how you define it it hasn't stayed together - the USSR collapsed, after all, and half of its population found itself in republics independent of Russia.
As for why the rest of it has stayed together, and most likely will - as I discuss there, Russia itself is very centralized, part of this because of the recentness of its expansion, but also the way it has developed, industrialized and urbanized. 15% of the population lives in and around Moscow alone, and over 75% lives in European Russia (and most of the population in the Asian part lives along the southern border). For all its many nationalities and its federalism that is an inheritance of Soviet nationality policy, it's still over 80% ethnic Russian, with just a few of its regions having a majority non-Russian population (and many of these not really being viable independent entities geographically or economically speaking). There aren't particularly strong regional identities in Russia - even the language itself is pretty uniform across the whole region, with very little variation.
So - Russia could break up under extreme circumstances: nothing is impossible. This is more or less what happened in 1917. But even in the case of the Russian Civil War it's very hard to see how this would be a stable long-term solution: pretty much whoever controls the heartland of European Russia (around Moscow, St. Petersburg and the Volga Valley) has inherent strategic advantages compared to other peripheral areas, and many of those latter don't have strong enough national identities or the resources to resist (or want to resist) that center.