[aaron695]

The[insert relevant law enforcement] could subpoena the VPN company for your IP address. So that wouldn't be 'anonymous'.

Telling the blockchain about your bitcoins and their transactions would also leak your IP.

To be anonymous you need to do all transactions from anonymous internet and get all your stuff anonymously.

Perhaps a purchased ebook downloaded from TOR.

You can wash your coins of course, I think it currently requires trust in the company doing it and if not done correctly might still leave a trace.

Of course the real world is different, would the FBI do enormous op sec to catch a small time crook. It's more about risk management.