Is this really our war, and if so - why?
Breaking Germany-Russia partnership benefits Poland. Aiding Ukraine supports our ally and hurts Russian imperial ambitions. Putting pressure on Germany to aid Ukraine (now also with tanks!) prevents Berlin's return to amicable relations with Moscow in the foreseeable future. Building transatlantic energy relations (all these LNG terminals) helps to close European markets to Russian energy resources, not only today, but also tomorrow.
Oh, I do care about how many Ukrainians die and hope their casualties will be as low as possible for them to achieve their war goals. If you do not believe I do it for humanitarian or moral reasons, than consider the practical ones: if Ukraine manages to keep its independence in this war, it will be integrated into NATO and become our not only formal, but also closest and most valued ally within the Alliance. Since Russia is the only enemy able to even scratch NATO, and we together will form its first line of defense, we will be working very closely. Of course I hope our neighbor and ally manages to keep its strength - and a hope for demographic rebirth in future years.
I also do believe that Ukraine's loss in this war would not end conflicts in Europe. On the contrary, it would make them more possible. Russia overconfident with its victory 'over whole NATO' in Ukraine would be more willing to test the Alliance, and that may escalate into a full scale war, only this time on a much larger scale. Hence, I hope that Ukraine manages to prevail and keep its independence. Such victory would result in a deep crisis of Russian statehood and open up another 'window of opportunity' (like after the fall of Soviet Union) for more countries - like Moldavia, Georgia and perhaps one day even Belarus - to escape the toxic influence of Moscow.