During each assimilation attempt, the natural wonder is injured. And during each attempt, the life pill takes in more power than it can handle, so it explodes and dies.
He knew this before. But when he saw nine life pills pulling on one natural wonder trying to assimilate it, he noticed that the power they were each pulling from the natural wonder had become weaker and milder.
He also noticed that the natural wonder itself was weakening and getting injured faster than normal because of the nine sources of stress.
These two phenomena reduced the stress on each life pill and increased their chances of assimilating the natural wonder as a whole. He became intrigued and hopeful when he saw this.
He thought to himself, "Maybe they have a chance. They might just have a chance."