I don’t think people mean to blindly start a business that you have no idea about. What they mean is that you can never have all the answers and so you just need to start and figure out stuff along the way. It doesn’t matter how old a business is, you’ll still have new issues to deal with. It’s impossible to know everything before you start. There is always risk involved. It’s up t you to minimize that risk as much as possible by being well-prepared.