It is an unsecured loan, however the lender matches borrowers with investors rather than directly loaning out the money from themselves.
If the “investors” you speak of---and the term would be more accurately stated as “lenders”---are individuals, then the money they are lending is coming out of their accounts, and reducing their accounts by the amount loaned. Those are real and legitimate loans that should ethically and legally be repaid. The loans that can be cancelled are really magic tricks. They are the vast majority of instances where Visa, MasterCards, and other unsecured lines of credit received money that the financial institutions created under the Federal Reserve System and never had any deduction out of their accounts.
Rather, they simply did a computer entry, where they created it out of thin air. This is called the Mandrake Mechanism. They have nothing at risk. The fact that they pretend otherwise is fraud.
Thus the reason we have a 100% success rate in cancelling those debts is that we challenge them to prove that they really loaned something, that money really came out of their accounts and that they had something at risk. They can’t do it. The type of loans being talking about here would be legitimately repayable, UNLESS they were made by banks or financial institutions under the Fed system using the Mandrake Mechanism.