How do you know? Have you experienced everything in the universe or universes? The next plane of existence could be phenomenal. Read or listen to Alan Watts. He opened my mind to a whole new level of thinking.
Its also like the saying "all life is sacred". We believe that because we are alive. Its self serving in nature. And how fast does that belief dissolve when we see a spider on our wall, or ants on our counters? Its all selective and biased.
The best? My good friend let me introduce you to a thing called tacos lol.