Debt is the amount owed on a loan. There is no loan taken out, nor terms. There is no creditor. There is no term sheet. There is no capital. There is no security. There is no debt. It's imaginary. Not imaginary like how money is imaginary. It literally does not exist, in any way shape or form, other than as myth, parable, metaphor, or ghost story. Better not incur tech debt, the boogie man will get ya! (Or, as is much more popular as a rationalization: that debt as fiscal policy is actually a good thing, so 'tech debt' must similarly be good)
If it was real debt, the bank would have called in their loans on the deadbeats and forced them to fix their shit, far more often than actually happens. But it's not debt. It's just lazy people putting off what they don't feel like doing.
The idea behind tech debt is just the state of cheating yourself by doing a shitty thing for short-term gain. It has nothing to do with money. It's an intellectual rationalization for being lazy. ("Hey, it's no big deal that I didn't add security to the web service, it's just tech debt! I'll pay it back later!")
It's like drinking too much booze, eating too much pizza, and not working out, because it's easier to do that now, with the promise of working out later to relieve the "debt". But you never stop pigging out, and you never start working out. It's just cheating yourself in the future to be lazy today with no material consequence.