Maybe because it is very complex to convert the money from crypto and it requires KYC where personal details are required before getting the money.
So they prefer the traditional thing and besides not all of them are capable of hijacking cryptocurrency.
It's obvious that it's easy for criminals to use the traditional which has easier transaction processes.
I hope that criminals will not shift their targets to crypto, because if that happens, of course there will be many people who will become the targets of their crimes later, indeed now many criminals (hackers) are starting to target to steal from the exchange but maybe only a few people are able to do it this, because it requires computer programming skills which may be above average for some people, but for traditional criminals of course fiat money can be an easy alternative for them and I think they also don't want to take the risk of targeting other people crypto assets because it is complicated process.