Potentially all the survivors of their world depend on this. No matter how small that number might be or may get.
At least three thousand people depend on this. That's enough to motivate them to try to refine what they worked on.
Even if all the previous attempts are - if no disastrous - quite ridiculous failures.
Sixteen people finish their part on the summoning ritual. The light forces most of them to look away, but it soon recedes.