I assume most of it is just people who want cheaper access to these models and don't mind subsidizing access via somebody who is simultaneously distilling the model.
This is about controlling who gets to use the tokens for what, not about payment fraud.
This is about people circumventing the model company's attempts to protect their intellectual "property" (which, if you insist on that incoherent usage of the word "property", they themselves stole from the rest of us).
It's equivalent to buying a DVD in the US which is region-locked to Asia. Grey market, not black market. If you use a stolen credit card to buy that DVD, well tat's a totally separate matter.