is life sacred ?
is all life sacred ?
all life, unless you are a plant, means death also, for all life subsists on other life.

is the life of a fox is more valuable than the chicken it feeds on ?

is the life of a human more valuable than the life of the chicken which was previously a chicken, is now a meal and is tomorrow equal parts human and poop ?

if yes, then life as such doesn't matter,  only utility.
taken to a logical extreme, cannibalism can be justified if a big enough utility can be found.

if not, what're you gonna do ?
 this is how you get fruitarians. 

we can't all be fruitarians.

 to sustain 1.2. 7.x billion people ( note, we aren't able to do this even now
WITH farmed meat, hunting, fishing etc),  you would need lots and lots of orchards
assuming no pesticides, you would still have displaced a huge amount of animals, birds, and insects, leading to their deaths.

or wait, if you could build a matrix, and stack humans 10 per sq. meter ( standing) , then you rope in all humans into a region built specially in a reclaimed desert or plain ( we have lots of these ) , just the size of New York City , then you have the rest of the planet free for planting orchards, and robots powered by ,well,  electricity derived from the pod humans, can run around and gather fruits from all over the world and bring them to the humans.
When the humans and the orchards and the robots reach a sustainable harmony, we can start exporting this setup to other planets. 
Sounds like the start of a great science fiction story. hopefully one in which things work out, and not go all dystopia where the heroine wakes up to recurring dreams of fruit gathering ( on earth, lacking electricity to generate simulations to keep humans engaged, the GoPro from the fruit gathering robots is collected and cut to form 3d for the matrix), and is told of her destiny by some local robots and hobos, and makes a trip back home to earth expecting a planet of orchards, only to find a silo (pods) and a cube (central software generator) and robots plucking fruits
//we could use terraforming robots that build platforms
//  logical terraforming to build programming platforms
// GPT3 based software and character generation modules in the cube
//a religion of chanting which uses a telephone book (?)

if my life is as sacred as all other life, then am i not required to sustain it, cost be damned ?
if you add that the universe cannot be known ( matrix - all that comes to our brain are electrical signals, plato - cave of shadows) , then i cannot know for sure that there is life elsewhere, only a reasonable facsimile of it.

the only working answer seems to be  "my life is sacred, i wouldn't answer for the rest"