Anybody can register a company, it's not a problem today. For example, anybody can register a company in Great Britain for $75 and that is why so many financial scams with Britain registration. We call on you to stop blindly believing words meant to cloud your judgment, such as “guaranteed”, “legal”, “registered”.
Indeed Bitcoin cryptocurrency is not registered anywhere and there is no evidence that it has a right to exist. But this does not prevent dozens of millions of people use cryptocurrencies. If something works well and benefits people, it doesn't matter whether it is registered or not.