Russia can sustain it but Ukraine cannot? Hahaha. Complete misreading of what is going on in this war.
Ukraine is not losing much men per day and can keep mobilizing for many more years to come. The biggest issue they face is the funding and weapons support from EU and they will continue to get that.
Russia on the hand, do not have any one to provide free money, China won't do it. They also lack the production capacity of the combined might of EU+US+Korea+Japan.
Russia much more likely to give up and break rather than Ukraine.
Already lost 13500 men in bodybags after Konstantinovka. Ukraine itself is constantly complaining about critical manpower shortages which is why they are hiring lots of mercenaries. You can see as time goes by, they are unable to hold the tempo of their counteroffensives, which tend to peter out after a continuous barrage of Russian firepower, the latest failed ones being in Kupyansk, which is unable to secure the east bank of the Oskil, and to regain Huliailpolye in Zaporizhye. The Russians have gobbled more territory east of the Oskil River including Kurolivka, while in Zaporizhye, the Russians have rolled back towards Pokrovske in the Dnepropetrovsk.
There are also significant breakthroughs all along the Kharkhiv front and another strategic settlement, Liman, is also about to fall. North of it, lies a huge pocket with Ukrainian forces towards Borova.
Every counterattack is a column of vehicles getting swarmed by Russian drones and the personnel getting picked away by drones. The latest being failed attempts towards Konstantinovka and Pokrovske. It's the same thing the Ukrainians used to post about Russian columns early in the war, but the situation is reversed.
Another reason why Ukrainian counterattacks are failing is that why they are copying Russian infiltration tactics, they do not have the manpower to storm and mop up occupied positions, and do sap work in clearing mines and so on anymore. These groups just bypass the Russian positions so they can plant flags at the rear, then end up getting picked off by FPV drones.
The ratio of bodybag exchanges between Russia and Ukraine has been going like 1000 Ukrainian bags to 30-50 Russian bags, and Russia is still keeping a huge pile of them because Ukraine cannot afford to pay the families of the deceased as it will be in the cost of billions. But as Orthodox Christians, they believe the body is sacrosanct as it will rise from the dead when Christ returns to the world at the end of days, so the bodies must be properly interred at it's rightful resting place.
As for Ukraine's budget, it has gone down annually from 125 billion each year to the last package of 90 billion. US isn't funding anything, you think it was Trump that withhold aid but he was already under pressure by the Pentagon who was alarmed by the rapid depletion of inventory. The caucus among the DoD and many Republicans is that they should focus and keep reserves facing China. Korea and Japan both have immense economic problems to deal with that is a separate topic. In fact if the Japanese yen continue to lose value, already at historic 40 year lows, they have to raise interest rates, or sell off US Treasuries which will be catastrophic to the US, because China isn't buying more TBs but gradually unloading what they have.
Let me remind you that thing called Iran left many Middle East refineries in a damaged state and the Homuz is still throttling the flow of oil from the Middle East and this has a domino effect world wide. The throttling of Urea from the Middle East --- ME, China, and Russia---are the biggest producers of it--- will have a deep effect in the global food production chain and you are wondering why the food prices in the grocery are so high. That's pushing many economies, from Japan to SEA to the brink.
Unrelated.
Ukrainians were using Mi-8s to shoot down drones but another Mi-8 has crashed after a Geran raid. All crew was lost. RIP. Russians were arming Gerans with missiles lately. This coming after a MiG-29 was shot down and a Su-24M was lost, the two likely lost from long range BVRAAMs.