Republicans falsely assume that everyone (or almost everyone) can succeed if they work hard enough. Democrats tend to have in mind those who need help.
Democrats are much more likely to realize that a high proportion of those who don't succeed, fail due to circumstances outside their control.
Some people are genuinely unfortunate, but you should also look at many of those who do get failures due to outside forces - what do they do afterwards? Many of them turn to drugs, alcohol, and various other things that only make things worse, or they don't even try to pick themselves back up(even if they are able). Sure, there are circumstances beyond your control, but it is up to you what you do once they have taken affect. I'm willing to help those who are willing to make the right decisions and work for themselves to pick themselves back up, but many people just don't even try so I don't care to bother with helping them - it's basically a wasted effort.