You're nitpicking. It's a hypotethical. He's trying to show how something that is not profitable right now might still have positive value.
The point of the question is whether you expect the person to earn enough that getting 50% of their life income would be worth 100, 1k, 10k etc. today, not 'how likely that person is to actually keep the deal'.
But that's exactly relevant to the point - the issue is that the details of the arrangement matter, which is relevant to the wider point: how are we expecting profit to be made? Gesticulating to size doesn't actually monetize something.
The point of the question is whether you expect the person to earn enough that getting 50% of their life income would be worth 100, 1k, 10k etc. today, not 'how likely that person is to actually keep the deal'.