Yes, you are renting from an owner just like renting DVC points. Some listings are from individual owners, some are from companies that manage the points and properties of owners. Is there risk? Like any financial transaction there is, however very few incidents of fraud have been reported in the decade I've been renting reservations. Still, you have be do your due dillegence as you would in any financial transaction.
Also, remember the risk cuts both ways. The renter has to be comfortable with you as well.