Okay, now this is rude. We're on public forum here sharing our opinions. Mine are based on the fact that I do know how online criminals operate as well as how money laundering work in my country.
I really can't speak about US and how FBI works, but again most of online criminals are not operate in the US.
Whatever. Go forward with your witch hunt. I personally never use crypto myself, though do some contract development on Eth-powered projects.
As about money laundering your opinion is one of a person living in western country with working institutions and strong legal frameworks. Unfortunately this isn't the case in many places around the globe. There is tons of countries where everything is just a question of % you want to pay.
Saddam Hussein who controlled his own currency (and even had his face on it) wanted US Dollars. The wanting of US Dollars (and laundering them) isn't limited to those who live in a western country.
I really can't speak about US and how FBI works, but again most of online criminals are not operate in the US.