Because that line of "enjoying your existence" making no mention of the monumental harm we cause to every biome on the planet is exactly the kind of selfishness that the button pushers would like to eradicate.
Causing harm to biomes is not the same thing as causing net harm to animals inside biomes. The base rate of harm done to animals inside biomes is immense and horrific.
You're doing crazy gymnastics right now. Eliminating biomes drives animals to extinction. In what world could you argue that doesn't deserve even a little moral consideration?
I'm not going to argue with someone who works this hard to be a contrarian.
It's not gymnastics, you just have no background on this topic.
Species are not moral subjects. Individuals are.
Killing an individual animal that could live a worthwhile life for longer is an individually bad act. Insofar as this happens in the process of species going extinct, that's bad. But it's also the default state of nature. Does replacing a forest with a city cause net harm to non-human animals? That's not clear. It might even be net good.
Does that mean we should destroy wilderness on purpose to prevent wild animal suffering? Not yet, we don't have the technology to mitigate knock-on effects, and it should be done a way that does not harm individuals. But I can't get behind viewing biome destruction as some kind of atrocity against the animals within them, at least not as a whole. (Some species have better lives than others).