I thought it would be cool to have my own TLD, but apparently it’s all managed by the ICANN, so you can’t just name your website with any TLD you want. There are different prices. But at least you can customize your second level domain. Why aren’t TLDs like this?
There’s nothing to scale. DNS servers are just an address book. There’s only 200 million entries active and visited. 1.1b entries otherwise, which; for a computer isn’t a lot.
DNS servers replicate down-stream, and the root servers maintain authority. A local SQLite file could handle this easily, and you could always run your own DNS server locally if you wanted to. But there has to be a central authority. That’s why you can have any TLD you want – you run your own DNS. But since nobody sees you as an authority, they won’t be using your DNS.