The market will quickly adjust to the point where spending $50 on tokens will on average give you a vulnerability valued at $50. Maybe $100 to account for your edge in having a better prompt and the risk of prison time you take in selling the exploit

In fact that may well be true today. OP didn't try to sell it to discover the true price the market is willing to pay. And we all know that "somebody paid $$$ for something similar in the past" is no guarantee that somebody else is willing to pay any significant sum for your thing today. If it was, startups would be a lot easier

I don't think OP got $500k , it's only clickbait in the title.

One LLM prompt can't get you $500K. Why would someone spend $500k instead of just prompting themselves?

Don't get all starry-eyed, the people owning those sites also have access to LLMs, so both the hacks and paydays are rare.