Blue, I'm with Windlesham on this one. There's a difference between theory and practice.
The textbooks say a synthetic put is created by a covered call, which is what I assume you are reffering to.
Mild correction: the important part is not that some textbook says it, but that it's a fact. Examining the P&L graph for both, or simply understanding put-call parity, should remove need to take it on faith.
But a covered call is equivlent to a cash-covered short put. Not a naked put where the amatuer seller doesn't have the cash to exercise. An important difference and there wouldn't be too many true naked put seller veterans in the market.
@Epicurus, there are two parts to this - and they're not in any way relevant to each other. Yes, the OP did something really silly by trading without having a clue about what he's doing - and made it much worse by doing it at scale. I don't think there's any argument or disagreement about that.
But you may want to review those text books for the other part. Put-call parity does not specify whether you have cash in your account or not. -P = +S -C ; that's the entire story, with no additional qualifiers. I'm certainly not the most experienced trader in the world, but I can guarantee that there are situations in trading where a naked put is exactly the right strategy... or it wouldn't exist at all.
(Have you ever noticed how "strategies" that aren't useful don't have a name? There's no "interlaced point-wide spreads all up and down the chain" strategy, or anything like "first 17 digits of pi worth of randomly-spotted puts and calls". But anyone trading options has heard of naked calls. I suggest there's a very strong reason for their existence.)