Sounds like you want a completely isolationist trade policy. How has that worked out for the US in the past? The only way to never pay another country to arm themselves against us or any other country is to never give them money, and unless we force them at gunpoint to give us what we want that is not going to happen.
> "we pay for the defense of people who won't pay to defend themselves"
The EU doesn't spend 0% on defense. Many of them are NATO members who are increasing their spending and who have demonstrated that they'll follow us into war after we are attacked (Afghanistan as an example). The US gets far more in soft power/geopolitical benefits out of our European allies and NATO members than we put in.