I'm not sure Ukraine wins a war of attrition in any meaningful way. Russia is also shockingly good at wars of attrition, and the entire Russian economy has been built around war with the West. Ukraine is a small state in comparison, and they are running out of men, money, and munitions so fast that even tipping the scales by 10x will sink Ukraine before Russia retreats from the territory they now own. In 2022, the goal would be to make it costly to acquire territory so ideas about attrition would have worked a lot better, but it's 2024 and Russia has already grabbed the land. Someone needs to go take it back.

Here's a memo for you on Russia's causus belli. You can claim that they didn't have a legitimate one (I don't think they did), but they had one that got them enough local and international support to work in both 2014 and 2022: https://www.ponarseurasia.org/vladimir-putins-casus-belli-fo...