I think you do not understand the framework you are living under and keeping you free. After WW2 and the formation of the UN we got a new world order, the whole Pax Americana is based on this order where collectively the world decided that invasions and annexation of territory is something we should all band together to fight against.
They're fighting to uphold this order, to show that it's not simply yet-another-treaty that a warring nation can break and take territory from another country with few consequences, where allying to countries doing that will be met with absolute resistance to hold to this ideal.
That's what we are paying for in Europe, if that doesn't have any value to you and you prefer to see it as a purely transactional interaction then go ahead to hold this opinion, other people believe in something further than simply tit-for-tat transactions. Morally speaking is a better way of living.