Could be, given where Russia was seen prior to February of 2022, as the second most powerful country in the world.
And being this is 2022-2023, it’s particularly bad given the interconnectedness of the world’s supply chains, economies, etc. as well as how high-tech things are - economic sanctions have an incredibly powerful bite now versus say a century ago. They can’t even put fucking airbags in their Lada shitboxes. They struggle to make more than a few dozen tanks a month, they are firing off nearly as many cruise missiles as they make every month. Gone are the days of peasants cranking out T-34 parts in low-tech factories. Now the parts they need for just their tanks rely on other countries’ manufacturing capabilities, which makes it harder for Russia.
As the former second most powerful nation in the world, this really has to sting for them. I’d consider these things major factors in your calculations of biggest blunder:
They’ve put their economy on the path that could break Putin’s grip on power. Economic problems doomed previous Russian governments in the 1910s and after the Afghanistan war (and US’s SDI) in the late 80s.
Russian demographics heading into 2022 were already suffering. Now they are inarguably worse as the prime male population has taken a hit with deaths and injuries. And many of those returning from the war will be broken and looked down upon, just as they were in Afghanistan and the two Chechen wars, and will struggle to provide for families. And they’ve lost potentially 750,000 young men in their prime who fled the country’s mobilization.
Russian influence on surrounding countries, including former Soviet republics, has been greatly weakened, and these countries even mock Russia.
NATO is strengthened and has been given a brand spanking new lease on life. NATO is also expanding in a way that has shocked everybody - Russia forced Finland and Sweden to drop their neutrality, which is stunning.
Ukraine is going to be left much, much stronger in the long run.
Putin has gutted Russia’s conventional military. They no longer have a reserve they can rely on. They could not stop a conventional invasion before it reached Moscow without nukes. They’ve lost so much institutional knowledge.
Putin has made Russia a vassal state of China, and India to a lesser extent. This is the biggest blunder. The Chinese will take advantage of them, and are.
Given Russia’s power in the world prior to last year, I feel like it could be the biggest blunder., especially since it was mostly an attack on a single neighbor a third it’s size, and not a full-on war of conquest against an entire continent.