Linear founders had "savings" from previous exits. Some of the early ones really were ramen-scale from what I can tell.

So that's one way to come up with the capital you need. Start something, grow it, sell it for $$, and invest that $$ in a new company that you hope will be worth $$$$. Rinse and repeat. You don't have to make it big on your first try!

A $4.2 million seed round from Sequoia also didn't hurt. Maybe they were able to eat pizza instead of ramen because of that.