The world's central banks and the big U.S. and European banks have covertly claimed de facto ownership of all securities listed on exchanges anyway, plus Blackrock is just part of the government along with big Wall Street banks, et c. It will be federally owned from the very beginning. Your "ownership" of securities is by law as of this year, your temporary, revokable license to it. Like streaming service purchases on Sony. You are no longer entitled to hold it permanently. You are only entitled to hold it until the company decides to take it away. It's legalized crime.

Will they also come after self-custodied bitcoin? How does one prepare in that scenario?

Sir. I bought btc years ago and on my trip to 'merica our boat wreck. I have no more btc.

Indeed, they already have.