How does startups make money?

I wonder this alot. Startups seem to get cash from venture capital firms, that just give money like that for a piece of the action when the startup has a financial structure where it can make money on it's own. But how is that all possible today, so much seem to be making free software without ever cashing out although a couple of million is enough to keep these small startup afloat, and these angel investor aren't in any hurry to make the quick buck, it's like chump change to them. So aren't all these company just waiting to jump ship and continue till they hit one that can stay afloat.