Embrace infinity already

If you accept infinity, then you can believe that the universe is infinite in size. That means that it is a statistical certainty that there is a planet out there where your favorite Touhou is real, and danmaku and magic are real. Isn't that something that you want? It won't work unless we all believe. Please believe, Anonymous.

If scientist don't think that the universe is infinite in size, then why is heat death the mainstream theory about the fate of the universe?