I remembered the concept I learned about the subject networking we had before. Internet is live network, no one owns the internet. With that regard, you can have access to the internet if you want to, you just need to trust and pay ISP but they don't really own a portion of the internet. Some people have just funded the transatlantic cables beneath the seabed but if we are to ask the world who owns it, no one. So why could we say internet is centralized then? Because of ISP? No. Because we are the one who could decide what ISP would we want. If they restricts and observe our browsing activity, it is just that, we let them to do so.