Goverment vs crypto

This might be a little rant and as well as asking.

How is it that we say cryptocurrency has no power within the government and it is people to people but the Feds and government could so easily take it away? 

I've been reading to many cases of the government confiscating  bitcoins. Most were in money laundering and some were when it was banned. How and why is this possible if this is supposed to be people to people and secure away from government. 

Anyone with anything on this much is appreciate