In the developed world, we do not feel obliged to be the worlds policeman and do not fund our services according to that idea.
Yes, they do tend to get a lot of money but it's not limitless.
Your use of the royal "we" is almost certainly mistaken. Even humble Canada is quite active in the use of its armed forces around the world.
Canada is active in all manner of UN peace operations. Since the first peacekeeping operation in 1956, Canada has accepted frequent requests to join UN operations around the world, whether in Cyprus, Bosnia, Haiti, or elsewhere. To date, over 125,000 Canadians have served in close to 50 UN missions
It would be easy to show similar commitments by Britain, Australia, and many other countries.
You are correct that about funding in that most of Europe is not meeting its defense spending targets agreed to within the NATO alliance.
Why you think that not meeting your defense obligations and misspending what you do have constitutes being part of "the developed world" shows the pitiful state of most of Europe's militaries. Even Britain is decimating its armed forces.