Even more important than the economic shrinkage, is the destruction of Russian industry (including military industry) through deprivation of technology access. This is also ignored by the parent comment. Russia can't rebuild or restock their military without the required external tech (much of which has been shown to depend on the US semiconductor industry). All of Russia's more modern military hardware requires foreign semiconductors, they're wildly incompetent in nearly all aspects domestically on advanced tech hardware. The sanctions are draining their military capabilities, in the present and for the next decade or so.
Russia is trending toward empty when it comes to their military inventory and they won't be able to replenish it as things stand. The only way they can is if China steps in and provides an epic scale infusion (which is not in China's interest).
Meanwhile the US can rev its military industrial complex to an extreme degree as it sees fit; and in tandem with Ukraine, obliterate Russia's military to the extent the Russians are dumb enough to continue occupying Ukrainian territory and sending more of their soldiers and hardware to the slaughter. The US hasn't even begun to seriously rev its production capabilities.
The equation there is Russia is fucked. Their national strength derives from energy + military power / power perception - one of those is heavily destroyed (courtesy of Ukraine's military + NATO weapons + sanctions).
Russia is so incompetent and drained they're having to source drones from Iran and go begging to North Korea.