network effects. If you are a marketplace or service you need both sides ramping up fast- the more users you get the more valuable it becomes and easier to attract more and so on.
It's like that. You start with bringing your cofounders together. Then you add your first customers. Then maybe you raise a little bit of friends and family money, and that lets you put more money into customer acquisition, which gets you more cofounders, which lets you get more revenue to hire a few more people, and raise more money, and so on.
So startups are like katamari damacy, and if you win, you end up picking up an entire industry.
Unrelated, but did you ever play Nobi Nobi Boy from the same creator?