Do they buy it outright of pay a fraction of the cost upfront then overpay for it on expensive monthly contracts? I very much doubt most of the 50% US market aren't tied into 24 month contracts.
1. Upwork connected the client and freelancer.
2. The client used someone else's money/credit to pay the freelancer.
3. The fraud was found out and the money refunded.
This, then, IMO is between the client, Upwork, and the police. Nothing to do with the freelancer. They are a victim in this fraud as well. Upwork have no right to demand money from the freelancer, their platform allowed the fraud, they're liable.