Bitcoin isn't anonymous - it is what is known as pseudonymous. The public ledger is completely transparent. If anything it has been an aid in tracing the flow of money/Bitcoin to paedophiles.
Many in the libertarian community (and those who want Bitcoin to be truly anonymous and fungible (like cash)) are as we speak devising methods that Bitcoin be truly anonymous (see Monero, Zcash etc). But as it stands. , it isn't.
Have scumbags used crypto currencies ? Yes, I'm sure they have and do. Much the same as Mexican drug cartels used HSBC and others for laundering money in sterling and dollars.
But what are you going to do, uninvent the Internet ( and Bitcoin is the Internet of money and value transference) because someone, somewhere has used it to watch porn or gamble outwith their jurisdiction ?
Meanwhile, the other 99.9% of us, that are innocent, have to be denied the greatest technological advance since the invention of the wheel ?
Anyhow, I'm aware this is off topic - so I"ll attempt to make some kind of a connection to the OP.
Did you know that for every £10k I have deposited the bank is allowed to magic into existence another £90k to lend out to you on your mortgage ? Except, they pay me 1.5% to borrow my £10k - but then are allowed to charge you between 3% and 16% (on credit cards) on the magicked into existence money

You could not make this s**t up.
And they get greedy.
Then they start lending it out to people that have no hope of paying it back.
Then they get
really greedy and start selling derivatives of high risk debt to unsuspecting and desperate states/people on the promise of stellar returns.
It all eventually goes a peary default shape and the banks start realising colossal losses.
But they can't be allowed to go bust. God no

, not these businesses.
Because they are too big to fail, you see, and too many of us have our life savings tied up with them.
So, on top of being perpetually scammed by their interest rates wizardry, we now get to be double scammed by paying for their losses from our taxes (RBS just announced another £469m loss for the third quarter BTW). And on top of that, the mother bank, the Bank of England, has to magic up several billion (well, half a trillion) into existence - thereby necessitating the reduction of interest rates to a level by which I am (or soon will be) paying the bank to hold my f***ing money - which, BTW, has the extremely unfortunate side effect that my old age will now be spent impoverished due to the bankrupt state of my companies final salary pension scheme (which is statutorily bound to disproportionately invest in interest paying gilts)
And so, with the benefit of hindsight, it looks very much like
the financiers knew all along that they were in an unassailable win-win situation. How else can we account for their actions ?
And you tell me a currency that doesn't rely on a central authority for its legitimacy, that cannot be magicked into existence, whereby commercial banks cannot play fast and loose with other people's money precisely because the supply of said currency is finite - you tell me it's for crooks ?
I suppose you might say that oftentimes a nascent technology might first be ceased upon by those with more underground tendencies - this is often the case, mostly cos crooks are oftentimes very savvy.
But if you ask me, the monetary system that we have in place today is about as crooked as it gets.
By design.