Because there are big problems, one should not solve the small problems? Because I know of aids, I should not give a dollar to the local begger?
Please stop this bullshit about aids orphans in Africa - it's just propaganda by the charity organisations who want you to give them money. Children are children everywhere in the world. Those aids orphans are not abandoned by Africans - every human being has the nurturing instinct. Neighbours are not letting orphans starve in Africa. Africa does not NEED you to solve this problem - it is a large problem, but it's not a critical problem.
There are WORSE things, but they are not sexy. There are men who work their entire life shoveling coal for hardly any money to survive, but nobody cares about them. They are not cute, they are not small, so they are abandoned.
Don't let those charity fat cats shape your perception of where help is needed. THINK first! And everyone cannot fight the same battle, we have to diversify and fight different battles. So if you see someone doing nothing, then ask him to do something. If you see people already helping in one way, don't try to make them do what you are already doing, otherwise all these other problems will get ignored.