I'm very much in favour of legalization of drugs.

But there are other crimes that create illicit money: extortion/blackmail, human/child trafficking/exploitation, murder for hire, theft, ransomware/malware, and whatever new horrible ideas get created next.

Making money laundering harder makes criminal activity less beneficial to commit. And while ending the illegal drug trade will greatly reduce the need for anti-money laundering organizations, it certainly won't end the need entirely.

Sure, and the government should be investigating people who have lots of suspicious cash. That's a lot different than penalizing people with private wealth just because they have it.

How do you expect the government to know about people who have lots of suspicous cash? That's what the reporting laws are intended to help detect...

They shouldn't unless they have reason to investigate me. I live in the US. I have a reasonable expectation of privacy and it shouldn't be a crime to not proactively confirm that I'm not committing crimes.

This seems like a very naive view. Plenty of people will want to launder money to support acts of violence regardless of what laws are on the books. When you want to kill somebody, you want to kill somebody.

It's already illegal to kill people. We don't also need to make it illegal to have $10,000 in cash without telling the government.

It's not really about child porn or drugs or whatever. It's about taxes.