Criminals and drug traffickers prefer fiat, because they find it an easy accessible than crypto. When transaction were made through cryptocurrency, the process is simple and there is chance of backtracking if small mistakes were made. People have a belief, cryptocurrency is much used for criminal activities, terrorism and darkweb needs. I don't say crypto isn't used, but compared to fiat it is very very small.

In recent days hackers prefer crypto currency. Because, they're technically skilled and knows how to bypass different parameters involved while a transaction is made. The world is at the very beginning days of crypto adoption. So, at present it isn't possible to spend big with cryptocurrency. There are possible ways, but everyone aren't good enough and strong to take such risks.