If I wire you some bitcoins for a suitcase full of cash, do you think that there may be some, ah, regulatory problems in this exchange?

What if I wire your bank account money in exchange for said suitcase of cash?

What if I'm a bank that credits your account, in exchange for said suitcase of cash, no questions asked?

(This is precisely what KYC laws exist to prevent.)

Yes technically it is. It would also be illegal to give someone Euros for USD so there are practical thresholds here that need to be crossed before anyone is going to press charges, but doing it regularly is definitely something that puts you at risk.