well, now I'm curious - within a p2p marketplace, risk only exists for sellers. if a buyer is 'scammed' (i.e. seller does not deliver) they can issue a chargeback - though the procedure with digital goods can get annoying. no equivalent process exists for sellers.
what kind of protection do you offer sellers?
In most cases, buyers are considered more vulnerable since they pay money upfront. However we do offer the same protection for sellers as well. First we will ban the scammer user. And then we will help the seller contact the venue/event organizer to void his/her tickets so that the other party can't make use of them. Next step will be try to get the seller new tickets (usually in this case will be will-call pick up) or issue seller the full amount of the face value of the tickets.