How does that apply to someone using it to pay for VPN service? Who cares what other people are using it for.
Also, many of those "criminals" are using it to buy shit like HRT because they can't get it where they live. Some others just want to get cheap cannabis gummies in states where it's already legal.
You shouldn't paint with such a broad brush.
USD is just as private, unless you're tracking serial numbers on bills, and even then... It would be like saying you don't use cash because it's used by criminals. Makes no sense.