For a sense of scale (only scale, money is definitely not the most important criteria), the EU currently spends twice as much on their military as Russia: https://en.wikipedia.org/wiki/List_of_countries_with_highest...
So if (when) American support disappears, I expect Russia to continue to not go anywhere fast while wasting a lot of lives in the process. I also expect this to surprise Putin, as he thinks Russia is a Great Power and therefore can only be stalling if Ukraine is supported by another Great Power and doesn't recognise that (1) Russia isn't, and (2) the EU kinda is, sort of, when it feels like acting with unity rather than as 27 different nations.
The sole reason Russia invaded Ukraine was that it was flirting too much with NATO.
Putin might be a lunatic, but he is not stupid.
Finland is a member.
Lithuania is a member.
The sad reality is that your logic is just a twisted pretzel to support the position you wish to take which is you support Russia's unprovoked invasion of Ukraine.