It's extremely difficult to track the owner of a particular wallet. Even though it's not impossible. This difficulty in tracing can be amplified through the use of bitcoin mixers. That's the reason why cyber criminals around the world uses cryptocurrency only. Take example from the recent attack on an American pipeline.
There are many ways to cash out such illegally obtained bitcoins. They can use bitcoin mixers to hide the trail of bitcoins and the sell off in any p2p marketplaces. Bot all p2p marketplaces require kyc until you reach a certain volume. There are darknet markets are well. It's unfortunate that bitcoin is actually empowering these miscreants.
It's not so difficult but the police has no time and the victim think it's not possible so they don't try. Such a scammer is involved in thousands of transactions and only one little mistake and the analytics software will catch him. If not now then somewhere in future. So ne scammer can sleep calm. The scammers brain may be think two or three steps depp in the blockchain but the software finds far deeper connections. Mixers and Monero forth and back might help but the scammers get lost in the high number of addresses to administrate and co-spend coins after mixing with other ones and the house of cards collapses. I was able to linkmore than 20% of a Wasabi Coinjoin trnasaction outputs to their inputs because of this users mistake. And this doesn't mean for 80% it works. It means if the scammer is doing 1000 transactions and fails on one then he will be caught earlier or later if the loss is not too low.