I really just don't find the argument of 'since I don't feel like all these big problems will ever be fixed there's no point in trying to fix anything' compelling at all. It's really just a form of nihilism. And one can do it with a frown or a smile, but it's still the same abdication of responsibility in the end.
It often seems to me that the world is just one problem piled on top of another, consecutive horrors with no conceivable end in sight, but to me, that is only *more* reason to do whatever good I can, to alleviate whatever suffering I may be able to, and to bring whatever joy is within my ability. Can I end all suffering? No. But can my choices bring more or less suffering in the world? Yes. Does it matter what I choose to do and how I choose to act towards others? Absolutely.