In addition to what others have said, prepare yourself. Many of the hatcheries that have been around have family members with advanced degrees in poultry science from major universities. They understand chicken nutrition and diseases, what is required to keep them healthy. They have a real clear understand how chicken reproduction works. They can analyze a hatch and see what went wrong or how to improve it. They have a pretty good knowledge of chicken genetics. They understand and know chickens and chicken care.
If you are going to ship chickens, you need to know what your shipping options are. That is basically your post office. They have regulations they have to follow and they have procedures that you have to follow. You also need to know what the laws are of various states. All will require NPIP, but Virginia will not allow chicks to be shipped in unless they have beed tested for another specific disease. Some states don't have the capability of testing for that specific disease so certain hatcheries don't ship to Virginia. And, of colurse, you need to understand the laws of your own state relative to your planned business. You probably need licenses and permits, probably regular inspections.
You have to decide on a business plan. Are you going to keep your own flocks for eggs or are you going to get your eggs from specific breeders? Are you going to hatch your own birds or drop ship like some do? What varieties and breeds are you going to offer? Are you going to specialize in a few varieties or breeds or be more of a generalist and offer many different varieties and breeds. Are you trying to keep it small where you handle everything or will you have employees? If you start hiring people, you have many labor laws you will need to know about.
I'm not trying to be negative. People start up new businesses all the time. Some of them even succeed. But for you to have a chance of success, you do need to know what is involved and prepare yourself for a lot of hard work and risk taking. If you have the passion and commitment, go for it.