What constitutes "risk"?

I was assuming financial risk is measured like a probability, as a percentage from 0% - 100%.

The starting position is 0 dollars, as you have nothing until you choose to accept $500,000. I agree there is no risk to this.

There is no chance at all you will end up with 9.5 million, or an additional 9.5 million. If you accept the $500,000 you are done. In leiu of accepting the $500,000 you may accept an opportunity to earn 10 million if you answer a question correctly.

At the end of the day, you will have: a) what you started with, or b) $500,000 more than that, or c) 10 million more than your starting point. You lose nothing in any outcome.

Please clarify this. First, you have been taking a risk working for 5 years without pay, accepting a promise of future payment. But let’s assume you’re boss is good for it and puts a pile of cash on front of you.

Scenario 1 has no risk: if your boss says, “Here, take it. I will give you an extra 9.5 million (or 10 million, or just $10 for that matter) if you can answer this question correctly. The cash on the desk is yours either way.”

Scenario 2 does have risk: your boss says, “You can have this money, or have 10 million more if you answer this question correctly, but if you answer wrong you get nothing at all.”

The difference the OP scenario and these two scenarios is that in these latter two scenarios, your starting point IS $500,000. You have earned it before you get to the table. But if there is no penalty for answering the question wrong, there is no risk in attempting to answer it.

You have to make a choice. You either get $500,000, or you get a question. If you choose $500,000 you have $500,000. If you choose the question you have (before answering the question) $0, but you gave up the $500,000 to be at this point. When you answer the question correctly you wind up with $10,000,000 in your pocket, for a net gain from answering the question correctly of $9,500,000. When you answer the question incorrectly you wind up with $0 in your pocket, for a net loss from answering the question incorrectly of $500,000.
We can rephrase this problem. I’ll give you $1 or a raffle ticket. If you take the raffle ticket and win nothing, you lost $1. Sure, the amount of money in your pocket did not change, but that doesn’t mean you did not lose $1. It’s the same as finding a $1 bill and then misplacing it – your net worth did not change, but it’s certainly a loss.