"We cannot fix the big problems." Oh really?

Hundreds of years ago, war and starvation were common in every nation. Now they are eradicated in half the world (rich countries still sponsor wars in distant lands, but those lands had their own wars anyway, just as ours once did). Most of this change has happened within the last century. So clearly we can fix the big problems if we want to.

Often it is trivially easy to fix problems. We could solve most of the world's urgent problems for a tiny, tiny fraction of what we spend on killing. But we choose not to.