They will never catch all of them, but they will catch some of them and nail them to the wall really good. (e.g. Martha Stewart)

If anything the privacy of Bitcoin is worse than conventional finance. In the case of Bitcoin the transaction log is in the record so anybody (the mafia, North Korea, ...) can find somebody connected with a transaction, put the squeeze on them till they talk, ...

In the case of conventional finance the feds can do that but they have to fill out a lot of paperwork, spend a lot of money, etc.