Courage doesn't play into it. It's a business, and people don't watch original material without a miracle of good timing and circumstances. An established property is always a safer bet, and thus generally a better investment.
With a prequel like this, I find it helpful to think of it as historical fiction, set within a fictional universe. I can enjoy a story about Robert Oppenheimer even though I know he succeeds in making the bomb, or find Apollo 13 riveting even though I know they all made it back. Tension over whether a character dies or not isn't and shouldn't be the only factor in whether a story is entertaining.