The simplest way to say how you are not understanding the situation is the Bitcoin is an inherently anti governmental concept.

It is built on a long history of governments screwing over their citizens thru inflation and is a form of money that is very hard for governments to stop.

For you to 'tell" them you own it is telling a potential enemy information about yourself that could be very critical for you.
If the US government doesn't know you own it and they (very likely) can't stop it or devalue it, then you are in control. You have the upper hand, so to speak.

Read the bitcoin white paper, 'The Sovereign Individual' and read some monetary history (for example, the inflation in the Roman days) for some context if you haven't already.