Russia is physically large, but pretty poor (its economy is only about the same size as that of Italy) and its defence industries are increasingly cut off from essential supplies. Russia has limited everything right now.
As we’ve seen over the last couple of years, well-trained competent military personnel are also in short supply.
>its economy is only about the same size as that of Italy
You've been fooled by your geriatric politicians.
"In the realm of foreign policy discourse, few memes have been more prevalent or misleading than the oft-cited comparison of Russia’s economy to that of Italy’s.
...
Yet error in this comparison lies in the reliance on measuring nominal GDP itself, as it fails to account for exchange rates and purchasing power parity (PPP), which accounts for the standard of living and productivity (and from there, per capita welfare and, importantly, resource use). Renowned French economist Jacques Sapir has pointed out the inadequacy of this metric, arguing that Russia’s GDP, when measured in PPP ($3.74 trillion in 2013, $4.81 trillion in 2021), is closer to Germany’s ($3.63 trillion in 2013, $4.85 trillion in 2021) than Italy’s ($2.19 trillion in 2013, $2.74 trillion in 2021). This is a crucial distinction, and it is both puzzling and troubling that so many continue to parrot the Russia-Italy comparison.
But even the PPP figures do not fully capture the significance of Russia’s economic power. Sapir further expanded his analysis in an essay for American Affairs, a policy journal, and noted that the PPP measurement “may not yet reflect the real importance of the Russian [economy] when strategic, geopolitical issues are at stake.”
Sapir notes that, over the past fifty years, Western economies have become increasingly dominated by service sectors, which, while contributing to GDP calculations, lose their importance during times of conflict. In such situations, it is the production of physical goods that matters, and by this measure, Russia’s economy is not only stronger than Germany’s but also more than twice as robust as France’s. Furthermore, Russia’s dominant position in the global energy and commodities trade—as it is a key producer of oil, gas, platinum, cobalt, gold, nickel, phosphates, iron, wheat, barley, buckwheat, oats, and more—provides it with substantial leverage over markets and economies, making it less susceptible to sanctions and less easily cowed by Western pressure. "[0]
Why? No clue - probably gross incompetence and corruption. The fact is that they have been at war for two years against what was one of the smallest militaries in Europe and still have not managed to obtain air superiority, indicating that they have some kind of shortage in the AA department.
