[thway0987]

OP's point is that if as a result of an intervention that is perceived as too direct by Putin, Russia wipes out Ukraine completely it will be a net loss to Ukraine. If on top of that he also wipes out Poland, then the loss will be even more dire. Russia has weapons it hasn't used yet, conventional and nuclear.

We can take a gamble and decide that Putin will decide to retreat because Poland donated some planes to the Ukrainians, but how much do you believe that will happen?