One comments says that venture funding is rocket fuel. That's true, but only if you actually have a rocket. You probably don't: you have a VW bug, or maybe a BMW. Almost no one has a rocket.
Anyway, I honestly don't understand the craving to hit a $billion business. It's completely unrealistic - it's just not going to happen. Creating a business that can support you, turning over 6-digits (instead of 9 or 10) is much more realistic. You won't get VCs on board for that, nor do you need them.