What major would be the best if I plan on making an entire network of websites? Knowledge from business, seo, and all that will be needed.
Just to digress for a moment, I will tell you that hardly anything you learn in university will be applicable to anything in business and in life. It may sound bitter, but that is what my experience has been... If you want to learn something, read about it, do it, fix your mistakes, and do it again...
If your ultimate goals in life are to own a network of websites, I think it would be far more beneficial to start now, learning about the various methods of Internet Marketing (which has its shared, and totally unique components to the marketing you learn in University), SEO, and possibly use that pool of funds to get your foot in the door. From what I have seen from both sides of the spectrum, there are much better resources on the internet to get you prepared for being on the internet, than in the courses at university. What you have to remember, is universities are all companies, which specialize in teaching, and giving you some paper that let other companies recognize you as having X base knowledge, and if they see your GPA, how good you were at accumulating and memorizing that knowledge. What it sounds like to me though, is that you have a very vague idea of what you want to do. "Making an entire network of websites" sounds like something, yes, a teenager would say. If your websites make more than a few thousand a month/year (which, if you want to make this your job, you will need to earn), then you will need to hire staff to manage them. What will your position be in the company once it grows? What will your position be in developing your network until then? You need to have the skills to handle all the steps. Just because in the beginning (which, as far as I can tell based on your question, this is as far as you have thought it through), you will do your own marketing and SEO, does not mean that if you make a decent living from your endeavors, it will not become more beneficial for you to hire others to do this while you focus on the larger aspects of managing your company. Do you want to be in charge, or do you want to be a Marketer? You can learn a lot about developing websites from the internet, and from info products - there are an abundance of resources that dwarf that which you will learn in a university, especially, as I said, since most universities have not caught up with internet marketing techniques, some of which change month to month, if not week to week. Is it worth going to university to have an education in management - something to fall back on in case your dream of a network is nothing more than a pipe dream combined with delusions of grandeur? What is it you really want to do?
You need both business skills and SEO skills if you want to be successful online without spending massive amounts of money on marketing.