I can guarantee it because NATO and the Western countries are only willing to sacrifice money. Once it escalates beyond that, they will pressure Ukraine to compromise with Russia or simply walk away as they have so many times before.
And I'm not sure why you think Ukraine can outlast Russia? Russia has 10x the GDP and 3x the population. They're also holding oil and gas over Western Europes heads.
Take a look at the exchange rate for the ruble. It's higher than before the war. Russia is forcing people to buy their gas with rubbles. They have way more leverage than you think they do.
And I'm not sure why you think Ukraine can outlast Russia? Russia has 10x the GDP and 3x the population. They're also holding oil and gas over Western Europes heads.
Take a look at the exchange rate for the ruble. It's higher than before the war. Russia is forcing people to buy their gas with rubbles. They have way more leverage than you think they do.