Most people don't have that. Most people HAVE to start small, or burn the midnight oil working on their MVP, trying to get traction. It's not because we necessarily want to, it's because we're hungry to win and we just don't have the firepower that our established competitors have.
It seems like there are a few different frames people have to think about startups. Some think of it like gambling (as you've said), some think startups are x-wings trying to take down the death star (with enough skill and a LOT of luck, a startup will hit it big), some want to reign startups back into being a business (start with an idea that makes money!), and then there are the founders in the trenches fighting on the daily. We're the guys that have been persistently working on our businesses, our projects, our hare-brained business models that just might work. We're grounded by reality - that this is very hard - but we just keep fighting down here. I'm going to stay on these front lines until I lead the guys here who believe in me to a decisive victory.