I don't see many people arguing that climate change will end life on Earth or something. But a mass extinction could mean, for example, that everything in the ocean larger than your hand dies. It could mean, for example, that lush forests full of a myriad of insects, birds, mammals, turn into wastelands. It could mean the extinction of huge swaths of animals, like goodbye raccoons, bears, squirrels, bison, wolves, deer. Or goodbye lizards, turtles, snails, snakes. Maybe it hits a link lower in the chain first, like bees, ants, and whole towers of the ecosystem collapse down from there.

When the dinosaurs were obliterated by the Chicxulub impactor 65 million years ago, 90% of land species also disappeared, never to reappear again. It took millions of years for mammals to emerge as the "victors" of that huge extinction event.

The viewpoint you espouse is just so hollow and frankly, repugnant. The thought that we can just stupidly smash incredibly intricate towers of evolution's genius, flub our precious time on this Earth to move from ignorantly and unintentionally knocking them over to actively raising a sledge hammer to them, justifying it to ourselves that "it will all be fine". Such a destructive attitude ruins everything for everyone. It's flippant and stupid, But it's ultimately, tragically, self-destructive.

It doesn't matter what we think. It's our actions.