There have been droughts in Africa, there have been civil wars in Africa, there have been hurricanes in the Caribbean, there have been typhoons in Asia and so on. Lots of other countries have been ravaged by war or natural disasters. Have we offered to take them all in, no, so why are the Syrians a special case. What puts them above all the other refugees in the world.
It's not that people don't care. It's a case of it happening in so many countries to so many people what can you really do about it. The cause - simply too many corrupt politicians.