Europe would not be able to sustain war of attrition with Russia

I don't think so; prior to 2026, the Russian economy was flourishing, partly due to very high crude oil prices and the existence of a "shadow fleet" of oil tankers.

Since 2026, that shadow fleet has been significantly hampered by Ukrainian actions in the Black Sea and elsewhere (notably, Norway and France have boarded vessels); China has faced pressure to stop buying Russian oil, and Russia is now selling its oil at half price because nearly nobody wants it (only India still buy it).

In an economy that was only driven by oil export (their Western gas pipeline had unfortunately exploded a few years ago), this is a terrible situation,

I have read posts online from (well-off) Russians who say they are somewhat despairing about the economic situation.