There are no boots on the ground from NATO in Ukraine; They receive support and aid in the form of money, weapons, intelligence, training, and material. They still have an economy, and have international trade, so it's not as if they're not paying for anything themselves. Much of the aid they receive is then spend on material from the country that gave the aid, arguably the US defense industry, amongst others, makes money of this war.

They've been keen to join NATO as a deterrent for Russian aggression, with very good reason. They're fighting an existential threat. Putin has made no secret that he doesn't consider Ukraine a country.

This concerns all of us in 'the West', because we've built our democracies around a concept of freedom and trade that the likes of Russia have been working very hard to destroy.