So you have got a groundbreaking idea that the world is in dying need of. Now, you just need to develop it. To do that, you need a team of people to build the tech and market the product. Then, you need resources to launch the product (smoothly); and you also need to scale.
Unless you are a scion, you will be needing quite a bit of external cash injection to finance these operations. This video by YouTuber The Rest of Us explains, very succinctly, the fundamentals of startup funding, all under 10 minutes. Enjoy!