I think it is more of indentured servitude than an uncollateralized loan, but not by much. Since getting rid of chattel slavery our society has generally found ways to eke our that unearned productivity from people via fractional servitude schemes. The (thin) line between an ISA and a loan is that the can discharge the loan through bankruptcy, im not certain you can do so as easily for an ISA.
Bankruptcy courts have pretty wide latitude to modify or terminate most types of agreements that create a financial obligation or liability. Certain types of student loans are excepted but not much else.
