Yes its a good question, like what portion of good can balance what portion of bad. I dont know for sure if prey animals enjoy their life or not, despite of having also a lot of nice moments.

The question is: if you know that u will die in a horrible way, would u still want to exist? Me not. But this is true for almost all preys. 99.9% of them will die in a horrible way. So the question is what can balance this amount of bad. For me there is not enough good in exchange.

So lets go 1 step further: if through the innovation of transhumanism we could make a lion vegan, would u support it?

I think there is no rational argument against this. Any argument against this would prefer the suffering of other animals more than a less exciting documentary.

So basically the question can be: is it better for an animal to exist (an animal that is a prey and can feel pain and all that stuff) or not exist rather?

It could be solved in a very peaceful way like slowly making every cm of the world controlled by cultivation for human use, what is happening now as well anyways.

Please dont answer btw based on cognitive dissonance, but try to think about this, it does not matter if its a comfortable thought or not. Only the logic.

Transhumanism says also something similar, but they want to make a lion vegetarian: that would be also a very nice thing to achieve if possible.